U.S. patent application number 16/443588 was filed with the patent office on 2019-12-26 for sanitary ware and method of manufacturing sanitary ware.
This patent application is currently assigned to LIXIL Corporation. The applicant listed for this patent is LIXIL Corporation. Invention is credited to Tadashi ASHIZAWA, Jaehoon CHOI, Shunzou IWASAKI, Shuji KAWAI, Hiroyuki MIYAMOTO, Toshinori MORI, Hideaki SAWADA, Kazuo TAKEUCHI, Isao YOSHINAGA.
Application Number | 20190389780 16/443588 |
Document ID | / |
Family ID | 68921251 |
Filed Date | 2019-12-26 |
United States Patent
Application |
20190389780 |
Kind Code |
A1 |
MORI; Toshinori ; et
al. |
December 26, 2019 |
SANITARY WARE AND METHOD OF MANUFACTURING SANITARY WARE
Abstract
Sanitary ware, including a ceramic base material, an upper glaze
layer positioned on a surface of the ceramic base material, and an
intermediate layer positioned between the ceramic base material and
the upper glaze layer, wherein the sanitary ware satisfies at least
one of the following conditions: a pore area ratio of 3% or less in
terms of a ratio of an area of pores present in a cut surface
obtained by cutting the upper glaze layer along the thickness
direction thereof, relative to an area of the cut surface, an
average pore size of 50 .mu.m or less as measured with respect to
the cut surface obtained by cutting the upper glaze layer along the
thickness direction thereof, and a difference of 50 .mu.m or less
between the maximum and minimum values of the thickness of the
upper glaze layer.
Inventors: |
MORI; Toshinori; (Tokyo,
JP) ; TAKEUCHI; Kazuo; (Tokyo, JP) ; IWASAKI;
Shunzou; (Tokyo, JP) ; YOSHINAGA; Isao;
(Tokyo, JP) ; MIYAMOTO; Hiroyuki; (Tokyo, JP)
; ASHIZAWA; Tadashi; (Tokyo, JP) ; SAWADA;
Hideaki; (Tokyo, JP) ; CHOI; Jaehoon; (Tokyo,
JP) ; KAWAI; Shuji; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LIXIL Corporation |
Tokyo |
|
JP |
|
|
Assignee: |
LIXIL Corporation
Tokyo
JP
|
Family ID: |
68921251 |
Appl. No.: |
16/443588 |
Filed: |
June 17, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C04B 41/5022 20130101;
C04B 41/86 20130101; E03C 1/18 20130101; C04B 41/009 20130101; C04B
41/89 20130101; C04B 41/52 20130101; E03D 11/02 20130101; E03C 1/14
20130101; C04B 41/009 20130101; C04B 33/00 20130101; C04B 41/52
20130101; C04B 41/4539 20130101; C04B 41/4582 20130101; C04B
41/5022 20130101; C04B 41/52 20130101; C04B 41/4539 20130101; C04B
41/5022 20130101 |
International
Class: |
C04B 41/50 20060101
C04B041/50; C04B 41/00 20060101 C04B041/00; C04B 41/86 20060101
C04B041/86 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 20, 2018 |
JP |
2018-117446 |
Jun 20, 2018 |
JP |
2018-117447 |
Claims
1. A sanitary ware, comprising: a ceramic base material; an upper
glaze layer positioned on a surface of the ceramic base material;
and an intermediate layer positioned between the ceramic base
material and the upper glaze layer, wherein a ratio of an area of
pores to an area of a cut surface obtained by cutting the upper
glaze layer along a thickness direction thereof is equal to or less
than 3%.
2. A sanitary ware, comprising: a ceramic base material; an upper
glaze layer positioned on a surface of the ceramic base material;
and an intermediate layer positioned between the ceramic base
material and the upper glaze layer, wherein an average pore size of
pores in a cut surface obtained by cutting the upper glaze layer
along a thickness direction thereof is equal to or less than 50
.mu.m.
3. The sanitary ware of claim 2, wherein the number of pores in the
cut surface is equal to or less than 120 per 1 mm.sup.2.
4. The sanitary ware of claim 1, wherein an average pore size of
pores in the cut surface is equal to or less than 50 .mu.m, and the
number of pores in the cut surface is equal to or less than 120 per
1 mm.sup.2.
5. The sanitary ware of claim 1, wherein the number of pores in a
cut surface obtained by cutting the intermediate layer along a
thickness direction thereof is equal to or less than 1,000 per 1
mm.sup.2, a ratio of an area of pores to an area of the cut surface
of the intermediate layer is equal to or less than 20%, and the
average pore size of pores in the cut surface of the intermediate
layer is equal to or less than 25 .mu.m.
6. The sanitary ware of claim 1, wherein a thickness of the upper
glaze layer is equal to or more than 100 .mu.m.
7. The sanitary ware of claim 1, wherein a thickness of the
intermediate layer is equal to or more than 200 .mu.m.
8. A method of manufacturing the sanitary ware of claim 1,
comprising: applying an intermediate layer composition for forming
the intermediate layer to a surface of the ceramic base material
either by dipping, pouring, applying, or spraying, and then drying;
and applying an upper glaze layer composition for forming the upper
glaze layer to the surface of the ceramic base material on which
the intermediate layer composition has been applied.
9. A method of manufacturing the sanitary ware of claim 1,
comprising: applying an intermediate layer composition for forming
the intermediate layer to a surface of the ceramic base material
either by dipping, pouring, applying, or spraying, and then firing
to obtain a primary fired body; and applying an upper glaze layer
composition for forming the upper glaze layer to the primary fired
body, and firing.
10. The sanitary ware of claim 2, wherein the number of pores in a
cut surface obtained by cutting the intermediate layer along a
thickness direction thereof is equal to or less than 1,000 per 1
mm.sup.2, a ratio of an area of pores to an area of the cut surface
of the intermediate layer is equal to or less than 20%, and the
average pore size of pores in the cut surface of the intermediate
layer is equal to or less than 25 .mu.m.
11. The sanitary ware of claim 2, wherein a thickness of the upper
glaze layer is equal to or more than 100 .mu.m.
12. The sanitary ware of claim 2, wherein a thickness of the
intermediate layer is equal to or more than 200 .mu.m.
13. A method of manufacturing the sanitary ware of claim 2,
comprising: applying an intermediate layer composition for forming
the intermediate layer to a surface of the ceramic base material
either by dipping, pouring, applying, or spraying, and then drying;
and applying an upper glaze layer composition for forming the upper
glaze layer to the surface of the ceramic base material on which
the intermediate layer composition has been applied.
14. A method of manufacturing the sanitary ware of claim 2,
comprising: applying an intermediate layer composition for forming
the intermediate layer to a surface of the ceramic base material
either by dipping, pouring, applying, or spraying, and then firing
to obtain a primary fired body; and applying an upper glaze layer
composition for forming the upper glaze layer to the primary fired
body, and firing.
15. A sanitary ware, comprising: a ceramic base material; an upper
glaze layer positioned on a surface of the ceramic base material;
and an intermediate layer positioned between the ceramic base
material and the upper glaze layer, wherein a difference between a
maximum value of a thickness of the upper glaze layer and a minimum
value of a thickness of the upper glaze layer is equal to or less
than 50 .mu.m.
16. The sanitary ware of claim 15, wherein an average pore size of
pores in a cut surface obtained by cutting the intermediate layer
along a thickness direction thereof is equal to or less than 25
.mu.m.
17. The sanitary ware of claim 15, wherein a ratio of an area of
pores to an area of a cut surface obtained by cutting the
intermediate layer along a thickness direction thereof is equal to
or less than 20%.
18. A method of manufacturing the sanitary ware of claim 15,
comprising: applying an intermediate layer composition for forming
the intermediate layer to a surface of the ceramic base material
either by dipping, pouring, applying, or spraying, and then drying;
and applying an upper glaze layer composition for forming the upper
glaze layer to the surface of the ceramic base material on which
the intermediate layer composition has been applied.
19. A method of manufacturing the sanitary ware of claim 15,
comprising: applying an intermediate layer composition for forming
the intermediate layer to a surface of the ceramic base material
either by dipping, pouring, applying, or spraying, and then firing
to obtain a primary fired body; and applying an upper glaze layer
composition for forming the upper glaze layer to the primary fired
body, and firing.
20. The sanitary ware of claim 15, wherein a ratio of an area of
pores to an area of a cut surface obtained by cutting the upper
glaze layer along a thickness direction thereof is equal to or less
than 3%.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the priority of Japanese Application
Nos. 2018-117446 and 2018-117447, each filed Jun. 20, 2018, the
entire contents of which are hereby incorporated by reference.
FIELD OF THE INVENTION
[0002] The present disclosure relates to sanitary ware and a method
of manufacturing sanitary ware.
BACKGROUND OF THE INVENTION
[0003] Conventionally, in sanitary ware such as a toilet bowl and a
washbowl, an upper glaze layer (a glaze layer) is formed on an
outermost surface thereof in order to inhibit adhesion of dirt or
to improve the design characteristics of the appearance.
[0004] In recent years, there has been a need to seek not only
hygiene but also a sense of luxury and quality in toilet and
washroom spaces where sanitary ware is installed. Quality is not
sensed only from design characteristics such as a color and a shape
and can be sensed from parts other than these. One of the
indicators indicating quality is image clarity. The image clarity
is a characteristic that expresses the sharpness of an image
reflected in a surface of sanitary ware, and the image clarity is
determined to be higher as the reflected image becomes clearer.
Sanitary ware with high image clarity gives an impression of high
quality. In addition, one of the indicators representing quality is
the "beauty" of sanitary ware. The term "beauty" relates to a
general aesthetic feeling that can be sensed from brilliance, a
tone of color, and the transparency of sanitary ware. Sanitary ware
in which "beauty" is perceived gives an impression of high quality.
For example, Japanese Patent Laid-Open No. 2012-72609 proposes
sanitary ware in which a glaze layer having improved image clarity
is formed on a surface of a ceramic base material. Japanese Patent
Laid-Open No. 2005-298250 proposes sanitary ware in which a first
colored glaze layer is formed on a surface of a ceramic base
material and a second transparent glaze layer is formed thereon. In
the sanitary ware disclosed in Japanese Patent Laid-Open No.
2005-298250, improvement of surface smoothness and improvement of
thermal shock resistance are achieved.
[0005] "Depth" can be exemplified as an indicator indicating
quality. The term "depth" relates to an expression of a
thickness-directional deepness of an upper glaze layer on a surface
of sanitary ware, and is recognized visually. Sanitary ware in
which "depth" is perceived gives an impression of high quality.
However, in the disclosure of Japanese Patent Laid-Open No.
2012-72609, the "depth" of sanitary ware was not taken into
consideration. In the sanitary ware of Japanese Patent Laid-Open
No. 2005-298250, the "beauty" of sanitary ware is not yet
satisfactory.
SUMMARY OF THE INVENTION
[0006] An object of this disclosure is to provide a sanitary ware
which is capable of further improving at least one of the "depth"
and the "beauty".
[0007] In general, sanitary ware with high image clarity has a
clear image reflected on a surface of the sanitary ware and tends
to give an impression of high quality. However, as a result of
intensive studies by the present disclosing party, even in the case
of sanitary ware having high image clarity, a thickness-directional
deepness was not necessarily sensed, and a correlation with "depth"
or "beauty" was not able to be found. The present disclosure seeks
a sense of luxury and quality of sanitary ware from a viewpoint
different from image clarity.
[0008] A sanitary ware provided herein can include a ceramic base
material, an upper glaze layer positioned on a surface of the
ceramic base material, and an intermediate layer positioned between
the ceramic base material and the upper glaze layer, wherein the
sanitary ware satisfies at least one of the following conditions: a
pore area ratio of 3% or less in terms of a ratio of an area of
pores present in a cut surface obtained by cutting the upper glaze
layer along the thickness direction thereof, relative to an area of
the cut surface, an average pore size of 50 .mu.m or less as
measured with respect to the cut surface obtained by cutting the
upper glaze layer along the thickness direction thereof, and a
difference of 50 .mu.m or less between the maximum and minimum
values of the thickness of the upper glaze layer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The invention will now be described, by way of example only,
with reference to the accompanying drawings, in which:
[0010] FIG. 1 is a cross-sectional view of sanitary ware according
to some embodiments; and
[0011] FIG. 2 is an example of a differential thermal analysis
(DTA) curve of an upper glaze layer of the sanitary ware, according
to some embodiments.
DETAILED DESCRIPTION OF THE EMBODIMENT
[0012] Sanitary ware 1 shown in FIG. 1 includes a ceramic base
material 10, an upper glaze layer 30 positioned on a surface of the
ceramic base material 10, and an intermediate layer 20 positioned
between the ceramic base material 10 and the upper glaze layer
30.
[0013] As used herein, the term "sanitary ware" means earthenware
products used around toilets and washrooms. Examples of the
sanitary ware 1 include a urinal, a toilet bowl, a toilet bowl
tank, a washbowl on a washstand, a hand washer and the like. In the
present specification, the term "ware" means earthenware obtained
by applying a glaze to a surface thereof using feldspar, pottery
stone, kaolin, and clay as raw materials, and firing it.
[0014] A thickness T1 of the sanitary ware 1 is not particularly
limited. In some embodiments the range of thickness T1 may be 1 to
50 mm. In some embodiments, the range of thickness T1 may be 2 to
30 mm. In some embodiments, the range of thickness T1 may be 3 to
20 mm. When the thickness T1 is equal to or more than the above
lower limit value (1 mm or more), the strength of the sanitary ware
1 is likely to be enhanced. When the thickness T1 is equal to or
thinner than the above upper limit value (50 mm or less), the
sanitary ware 1 is capable of being made lightweight so that it
becomes easy to handle. The thickness T1 of the sanitary ware 1 can
be measured, for example, using a vernier caliper.
[0015] In some embodiments, the range of image clarity of the
sanitary ware 1 may be from 80 to 99. In some embodiments, the
range of image clarity of the sanitary ware 1 may be from 85 to 99.
In some embodiments, the range of image clarity of the sanitary
ware 1 may be from 90 to 99. In some embodiments, image clarity of
the sanitary ware 1 may be 80 or more. In some embodiments, the
image clarity of the sanitary ware 1 may be 85 or more. In some
embodiments, the image clarity of the sanitary ware 1 may be 90 or
more. When the image clarity of the sanitary ware 1 is equal to or
more than the lower limit value (80 or more), it is easy to give an
impression of high quality. In the present specification, image
clarity refers to a distinctness of image (DOI) value measured by a
Wave-Scan DOI measuring device (Wave-Scan-DUAL, manufactured by BYK
Gardner).
[0016] Ceramic base material 10 may be a base material made by
forming a ceramic base material composition (also referred to as
ceramic base material sludge) into a predetermined shape using a
plaster mold or a resin mold and firing it at 1,100 to
1,300.degree. C. The ceramic base material composition contains one
or more materials selected from feldspar, pottery stone, kaolin,
clay and the like as raw materials. The ceramic base material
composition contains water. The range of the content of water
relative to the total mass of the ceramic base material composition
may be 30 to 50 mass %. The range of the content of water relative
to the total mass of the ceramic base material composition may be
30 to 40 mass %.
[0017] A thickness T10 of the ceramic base material 10 is not
particularly limited. The lower limit value of the thickness T10 of
the ceramic base material 10 may be 1 mm. The lower limit value of
the thickness T10 of the ceramic base material 10 may be 2 mm. The
lower limit value of the thickness T10 of the ceramic base material
10 may be 3 mm. The upper limit value of the thickness T10 of the
ceramic base material 10 may be 50 mm. The upper limit value of the
thickness T10 of the ceramic base material 10 may be 30 mm. The
upper limit value of the thickness T10 of the ceramic base material
10 may be 20 mm. In some embodiments, the range of thickness T10 of
the ceramic base material 10 may be 1 to 50 mm. In some
embodiments, the range of thickness T10 of the ceramic base
material 10 may be 2 to 30 mm. In some embodiments, range of
thickness T10 of the ceramic base material 10 may be 3 to 20 mm.
When the thickness T10 is equal to or more than the above lower
limit value (1 mm or more), the strength of the ceramic base
material 10 is likely to be enhanced. When the thickness T10 is
equal to or less than the above upper limit value (50 mm or less),
the ceramic base material 10 is capable of being made lightweight
so that it becomes easy to handle. The thickness T10 of the ceramic
base material 10 can be measured, for example, using a vernier
caliper.
[0018] The upper glaze layer 30 is a fired product of an upper
glaze layer composition for sanitary ware (hereinafter, also simply
referred to as an upper glaze layer composition). The upper glaze
layer 30 is a layer made of glaze (a glazing agent) for forming a
layer positioned on an outermost surface of the sanitary ware 1.
The upper glaze layer composition is a so-called glaze. The upper
glaze layer composition is slurry (sludge) in which glaze raw
materials are dispersed in water. The glaze raw materials are one
or more materials selected from silica sand, feldspar, lime, clay,
etc. In some embodiments, the range of the content of water
relative to the total mass of the upper glaze layer composition may
be 40 to 80 mass %. In some embodiments, the range of the content
of water relative to the total mass of the upper glaze layer
composition may be 40 to 70 mass %.
[0019] An average particle size of a solid content contained in the
upper glaze layer composition may be 20 .mu.m or less. The average
particle size of the solid content may be 15 .mu.m or less. The
average particle size of the solid content may be 10 .mu.m or less.
When the average particle size of the solid content contained in
the upper glaze layer composition is equal to or less than the
above upper limit value (20 .mu.m or less), it is easy to lower a
melting start temperature of the solid content contained in the
upper glaze layer composition. A lower limit value of the average
particle size of the solid content contained in the upper glaze
layer composition is not particularly limited, and is, for example,
0.1 .mu.m or more. In some embodiments, the range of the average
particle size of the solid content contained in the upper glaze
layer composition may be 0.1 .mu.m or more and 20 .mu.m or less. In
some embodiments, the range of the average particle size of the
solid content may be 0.1 .mu.m or more and 15 .mu.m or less. In
some embodiments, the range of the average particle size of the
solid content may be 0.1 .mu.m or more and 10 .mu.m or less. The
average particle size of the solid content contained in the upper
glaze layer composition can be adjusted, for example, by grinding
the glaze raw materials. For example, a ball mill can be
exemplified as a tool for grinding the glaze raw materials.
[0020] In the present specification, the "average particle size"
means a 50% average particle size (D50). D50 is a median diameter
on a number basis, and means an average particle size at 50% in a
cumulative distribution. The particle size can be measured, for
example, using a laser diffraction type particle size
distribution-measuring device ("MT3300EX (model number),"
manufactured by Nikkiso Co., Ltd.). The solid content contained in
the upper glaze layer composition is dried materials of the upper
glaze layer composition.
[0021] In some embodiments, the upper glaze layer composition may
comprise a composition containing 5 to 25 parts by mass of silica
sand, 20 to 40 parts by mass of feldspar, 5 to 15 parts by mass of
lime, and 1 to 5 parts by mass of clay. The upper glaze layer
composition may include a frit in addition to the above. The frit
is obtained by melting a frit raw material at 1,300.degree. C. or
higher and then cooling to produce an amorphous glass. When the
upper glaze layer composition contains the frit, the melting start
temperature of the upper glaze layer composition may be lowered. In
addition, the upper glaze layer composition may include the frit so
that the upper glaze layer composition is easily melted to be more
uniform and the number of pores in the upper glaze layer is easily
reduced. As the frit raw material, a composition which contains 40
to 70 mass % of silicon dioxide (SiO2), 5 to 15 mass % of aluminum
oxide (Al2O3), and 10 to 50 mass % of a total of sodium oxide
(Na2O), potassium oxide (K2O), calcium oxide (CaO), magnesium oxide
(MgO), zinc oxide (ZnO), strontium oxide (SrO), barium oxide (BaO)
and boron oxide (B2O3), with respect to the total mass of the frit
raw material, can be exemplified. The total content of each
component in the frit raw material is adjusted such that it does
not exceed 100 mass % with respect to the total mass of the frit
raw material.
[0022] When the upper glaze layer composition contains the frit,
the lower limit of the content of the frit relative to the total
mass of the solid content contained in the upper glaze layer
composition may be 50 mass %. The lower limit of the content of the
frit relative to the total mass of the solid content contained in
the upper glaze layer composition may be 70 mass %. The upper limit
of the content of the frit relative to the total mass of the solid
content contained in the upper glaze layer composition may be 100
mass %. For example, the range of the content of the frit relative
to the total mass of the solid content contained in the upper glaze
layer composition may be 50 to 100 mass %. The range of the content
of the frit relative to the total mass of the solid content
contained in the upper glaze layer composition may be 70 to 100
mass %. When the content of the frit is equal to or more than the
above lower limit value (50 mass % or more), the melting start
temperature of the upper glaze layer composition is easily lowered.
The content of the frit relative to the total mass of the solid
content contained in the upper glaze layer composition is adjusted
such that it does not exceed 100 mass %.
[0023] The melting start temperature of the upper glaze layer
composition can be defined by any of the first melting temperature,
the second melting temperature, and the third melting temperature.
The first melting temperature is measured by the following
measurement method 1-1.
[0024] <Measurement Method 1-1>
[0025] A differential thermal analysis (DTA) measurement is
performed using alumina powder as a reference substance and the
dried materials of the upper glaze layer composition for sanitary
ware as a sample powder, and a DTA curve is obtained. In a region
exceeding 700.degree. C. in the obtained DTA curve, a temperature
of the reference substance at the earliest inflection point where a
potential difference .DELTA.V decreases is taken as the first
melting temperature. The potential difference .DELTA.V corresponds
to a value .DELTA.T obtained by subtracting a temperature of the
reference substance from a temperature of the sample powder. A
temperature of the reference substance at the earliest inflection
point where the potential difference .DELTA.V increases in a
temperature region higher than the first melting temperature is
taken as the second melting temperature.
[0026] The DTA curve is obtained by performing the DTA measurement
using a differential thermal analysis (DTA) device. The DTA
measurement may be a thermogravimetric differential thermal
analysis measurement (TG-DTA) measurement. In the DTA measurement,
alumina powder is used as the reference substance, and the dried
materials of the upper glaze layer composition are used as the
sample powder. The dried materials of the upper glaze layer
composition are obtained, for example, by heating the upper glaze
layer composition to 20 to 110.degree. C. to evaporate the water.
The amount of water with respect to the total mass of the dried
materials of the upper glaze layer composition is, for example, 0
to 1 mass %. In the DTA measurement, the potential difference
.DELTA.V is measured as a function of temperature while changing
the temperature of the sample powder and the temperature of the
reference substance using a specific program. The potential
difference .DELTA.V corresponds to the value .DELTA.T obtained by
subtracting the temperature of the reference substance from the
temperature of the sample powder ((the temperature of the sample
powder)-(the temperature of the reference substance)). In the DTA
curve, among inflection points appearing in a region where the
temperature of the reference substance exceeds 700.degree. C., the
earliest inflection point where the potential difference .DELTA.V
decreases is taken as the first inflection point. The temperature
of the reference substance at the first inflection point is taken
as the first melting temperature. Among inflection points appearing
in a temperature region higher than the first melting temperature,
the earliest inflection point where the potential difference
.DELTA.V increases is taken as the second inflection point. The
temperature of the reference substance at the second inflection
point is taken as the second melting temperature.
[0027] The TG-DTA graph shown in FIG. 2 is obtained when the TG-DTA
measurement of the upper glaze layer composition for forming the
upper glaze layer 30 of the sanitary ware 1 is performed. In the
TG-DTA graph, the horizontal axis represents the temperature
(.degree. C.) of the reference substance. The first axis of the
vertical axis represents a mass change (mass %) of the sample
powder. The second axis of the vertical axis represents the
potential difference .DELTA.V (.mu.V). The potential difference
.DELTA.V corresponds to the value .DELTA.T obtained by subtracting
the temperature of the reference substance from the temperature of
the sample powder. In FIG. 2, a curve C1 represents a TG curve. A
curve C2 represents a DTA curve. In the curve C2, the potential
difference .DELTA.V increases as the temperature of the reference
substance increases, and the first inflection point P1 appears in
the region where the temperature of the reference substance exceeds
700.degree. C. At the first inflection point P1, it is considered
that the upper glaze layer composition starts melting and a glass
structure of the upper glaze layer composition starts to be
loosened. An intersection point between a tangent drawn to the
curve C2 when the slope of the curve C2 (an amount of increase of
.DELTA.V/an amount of increase of the temperature of the reference
substance) is a maximum and a tangent drawn to the curve C2 when
the slope of the curve C2 is a minimum is given as the first
inflection point P1. The temperature of the reference substance at
the first inflection point P1 is the first melting temperature. The
first melting temperature is determined in the same manner as in a
method of determining an extrapolation melting start temperature in
a general TG-DTA graph (see JIS K7121-1987). In the curve C2,
.DELTA.V decreases after the first inflection point P1 appears, and
the curve C2 has the second inflection point P2 in which .DELTA.V
increases again. At the second inflection point P2, it is
considered that the upper glaze layer composition is melted and the
glass structure of the upper glaze layer composition is completely
loosened. An intersection point between a tangent drawn to C2 when
the slope of C2 is a minimum and a tangent drawn to C2 when the
slope of C2 becomes positive is given as the second inflection
point P2. The temperature of the reference substance at the second
inflection point P2 is the second melting temperature. The second
melting temperature is determined in the same manner as in a method
of determining a melting peak temperature in a general TG-DTA graph
(see JIS K7121-1987).
[0028] In the DTA measurement, the lower limit value of the mass of
the reference substance may be 5 mg. The upper limit value of the
mass of the reference substance may be 50 mg. For example, the
range of the mass of the reference substance may be 5 to 50 mg. In
the DTA measurement, the lower limit value of the mass of the
sample powder may be 5 mg. The upper limit value of the mass of the
sample powder may be 50 mg. For example, the range of the mass of
the sample powder may be 5 to 50 mg. In the DTA measurement, the
lower limit value of the heating temperature for obtaining the
dried materials of the upper glaze layer composition may be
20.degree. C. The upper limit value of the heating temperature for
obtaining the dried materials of the upper glaze layer composition
may be 110.degree. C. For example, the range of the heating
temperature for obtaining the dried materials of the upper glaze
layer composition may be 20 to 110.degree. C. In the DTA
measurement, the lower limit value of the heating rate at the time
of heating the sample powder may be 2.degree. C./minute. The upper
limit value of the heating rate at the time of heating the sample
powder may be 10.degree. C./minute. For example, the range of the
heating rate at the time of heating the sample powder may be 2 to
10.degree. C./minute.
[0029] The lower limit value of the first melting temperature of
the upper glaze layer composition may be 800.degree. C. The lower
limit value of the first melting temperature of the upper glaze
layer composition may be 820.degree. C. The lower limit value of
the first melting temperature of the upper glaze layer composition
may be 840.degree. C. The upper limit value of the first melting
temperature of the upper glaze layer composition may be
1,050.degree. C. The upper limit value of the first melting
temperature of the upper glaze layer composition may be
1,000.degree. C. The upper limit value of the first melting
temperature of the upper glaze layer composition may be 950.degree.
C. For example, the range of the first melting temperature of the
upper glaze layer composition may be 800 to 1,050.degree. C. The
range of the first melting temperature of the upper glaze layer
composition may be 820 to 1,000.degree. C. The range of the first
melting temperature of the upper glaze layer composition may be 840
to 950.degree. C. When the first melting temperature of the upper
glaze layer composition is equal to or higher than the above lower
limit value (800.degree. C. or more), generation of bubbles when
firing the upper glaze layer composition is easily inhibited. When
the first melting temperature of the upper glaze layer composition
is equal to or less than the upper limit value (1,000.degree. C. or
less), the bubbles generated when firing the upper glaze layer
composition easily diffuse into the atmosphere.
[0030] The second melting temperature is measured by the above
measurement method 1-1. The lower limit value of the second melting
temperature of the upper glaze layer composition may be 850.degree.
C. The lower limit value of the second melting temperature of the
upper glaze layer composition may be 870.degree. C. The lower limit
value of the second melting temperature of the upper glaze layer
composition may be 900.degree. C. The upper limit value of the
second melting temperature of the upper glaze layer composition may
be 1150.degree. C. The upper limit value of the second melting
temperature of the upper glaze layer composition may be
1100.degree. C. The upper limit value of the second melting
temperature of the upper glaze layer composition may be
1050.degree. C. For example, the range of the second melting
temperature of the upper glaze layer composition may be 850 to
1,150.degree. C. The range of the second melting temperature of the
upper glaze layer composition may be 870 to 1,100.degree. C. The
range of the second melting temperature of the upper glaze layer
composition may be 900 to 1,050.degree. C. When the second melting
temperature of the upper glaze layer composition is equal to or
higher than the above lower limit value (850.degree. C. or more),
generation of bubbles when firing the upper glaze layer composition
is easily inhibited. When the second melting temperature of the
upper glaze layer composition is equal to or less than the above
upper limit value (1,150.degree. C. or less), the bubbles generated
when firing the upper glaze layer composition easily diffuse into
the atmosphere.
[0031] The lower limit value of the difference between the second
melting temperature and the first melting temperature of the upper
glaze layer composition (also referred to as the upper glaze layer
melting temperature difference) may be 50.degree. C. The lower
limit value of the upper glaze layer melting temperature difference
may be 60.degree. C. The lower limit value of the upper glaze layer
melting temperature difference may be 70.degree. C. The upper limit
value of the upper glaze layer melting temperature difference may
be 120.degree. C. The upper limit value of the upper glaze layer
melting temperature difference may be 100.degree. C. The upper
limit value of the upper glaze layer melting temperature difference
may be 90.degree. C. For example, the range of the upper glaze
layer melting temperature difference may be 50 to 120.degree. C.
The range of the upper glaze layer melting temperature difference
may be 60 to 100.degree. C. The range of the upper glaze layer
melting temperature difference may be 70 to 90.degree. C. When the
upper glaze layer melting temperature difference is equal to or
more than the above lower limit value (50.degree. C. or more), an
average pore size of pores generated when the upper glaze layer
composition is fired is easily reduced. When the upper glaze layer
melting temperature difference is equal to or less than the above
upper limit value (120.degree. C. or less), generation of pores
when firing the upper glaze layer composition is easily inhibited.
The upper glaze layer melting temperature difference is determined
by subtracting the first melting temperature of the upper glaze
layer composition from the second melting temperature of the upper
glaze layer composition.
[0032] The first melting temperature of the upper glaze layer
composition can be adjusted on the basis of a type of the glaze raw
material, a blending proportion of the glaze raw material, the
average particle size of the solid content of the upper glaze layer
composition, and a combination thereof. The second melting
temperature of the upper glaze layer composition can be adjusted
similarly to the first melting temperature of the upper glaze layer
composition.
[0033] The third melting temperature is measured by the following
measurement method 1-2.
[0034] <Measurement Method 1-2>
[0035] The dried materials of the upper glaze layer composition for
sanitary ware are press-molded to obtain a cylindrical sample.
Light is radiated while heating the obtained cylindrical sample. A
light amount of the reflected light reflected by a surface of the
cylindrical sample is measured. The earliest temperature where the
light amount of the reflected light is ten times or more the light
amount of the reflected light detected at the beginning of
glistening is taken as the third melting temperature.
[0036] In the measurement method 1-2, the cylindrical sample is
obtained by press-molding the dried materials of the upper glaze
layer composition for sanitary ware. The lower limit value of the
diameter of the cylindrical sample may be 2 mm. The upper limit
value of the diameter of the cylindrical sample may be 10 mm. For
example, the range of the diameter of the cylindrical sample may be
2 to 10 mm. The lower limit value of the height of the cylindrical
sample may be 5 mm. The upper limit value of the height of the
cylindrical sample may be 20 mm. For example, the range of the
height of the cylindrical sample may be 5 to 20 mm. The lower limit
value of the mass of the cylindrical sample may be 100 mg. The
upper limit value of the mass of the cylindrical sample may be 500
mg. For example, the range of the mass of the cylindrical sample
may be 100 to 500 mg. The lower limit value of the pressure for
press-molding the dried materials of the upper glaze layer
composition may be 10 MPa. The upper limit value of the pressure
for press-molding the dried materials of the upper glaze layer
composition may be 50 MPa. For example, the range of the pressure
for press-molding the dried materials of the upper glaze layer
composition may be 10 to 50 MPa. The light amount of the reflected
light is a value obtained such that the reflected light is taken by
a digital camera with a telephoto lens and is converted to the
number of pixels by an image processing system. The light amount of
the reflected light when heating the cylindrical sample is measured
every 1.degree. C. The "beginning of glistening" means that the
light amount of the reflected light reflected by the surface of the
cylindrical sample is not zero. The lower limit value of the
heating rate at the time of heating the cylindrical sample may be
1.degree. C./minute. The upper limit value of the heating rate at
the time of heating the cylindrical sample may be 10.degree.
C./minute. For example, the range of the heating rate at the time
of heating the cylindrical sample may be 1 to 10.degree. C./minute.
The lower limit value of the light amount of the light radiated to
the cylindrical sample may be 500 lumens. The upper limit value of
the light amount of the light radiated to the cylindrical sample
may be 2,000 lumens. For example, the range of the light amount of
the light radiated to the cylindrical sample may be 500 to 2,000
lumens. At the third melting temperature, it is considered that the
upper glaze layer composition starts melting and the glass
structure of the upper glaze layer composition is completely
loosened.
[0037] The lower limit value of the third melting temperature of
the upper glaze layer composition may be 850.degree. C. The lower
limit value of the third melting temperature of the upper glaze
layer composition may be 870.degree. C. The lower limit value of
the third melting temperature of the upper glaze layer composition
may be 900.degree. C. The upper limit value of the third melting
temperature of the upper glaze layer composition may be
1,150.degree. C. The upper limit value of the third melting
temperature of the upper glaze layer composition may be
1,100.degree. C. The upper limit value of the third melting
temperature of the upper glaze layer composition may be
1,050.degree. C. For example, the range of the third melting
temperature of the upper glaze layer composition may be 850 to
1,150.degree. C. The range of the third melting temperature of the
upper glaze layer composition may be 870 to 1,100.degree. C. The
range of the third melting temperature of the upper glaze layer
composition may be 900 to 1,050.degree. C. When the third melting
temperature of the upper glaze layer composition is equal to or
higher than the above lower limit value (850.degree. C. or more),
generation of bubbles when firing the upper glaze layer composition
is easily inhibited. When the third melting temperature of the
upper glaze layer composition is equal to or less than the above
upper limit value (1,150.degree. C. or less), the bubbles generated
when firing the upper glaze layer composition easily diffuse into
the atmosphere.
[0038] The third melting temperature of the upper glaze layer
composition can be adjusted similarly to the first melting
temperature of the upper glaze layer composition.
[0039] When the melting start temperature of the upper glaze layer
30 is determined from the sanitary ware 1 including the upper glaze
layer 30, the first melting temperature and the second melting
temperature are measured by the following measurement method
2-1.
[0040] <Measurement Method 2-1>
[0041] A DTA measurement is performed using alumina powder as a
reference substance and the powder of the upper glaze layer 30 as a
sample powder, and a DTA curve is obtained. In the region exceeding
700.degree. C. in the obtained DTA curve, a temperature of the
reference substance at the earliest inflection point where the
potential difference .DELTA.V (.mu.V) decreases is taken as the
first melting temperature. The potential difference .DELTA.V
(.mu.V) corresponds to the value .DELTA.T obtained by subtracting
the temperature of the reference substance from the temperature of
the sample powder. In a temperature region higher than the first
melting temperature, a temperature of the reference substance at
the earliest inflection point where the potential difference
.DELTA.V increases is taken as the second melting temperature.
[0042] The powder of the upper glaze layer 30 may be obtained, for
example, by appropriately cutting and grinding the upper glaze
layer 30. Conditions for the DTA measurement are the same as the
conditions for the DTA measurement in the above measurement method
1-1. The first melting temperature of the upper glaze layer 30 is
the same as the first melting temperature of the upper glaze layer
composition. The second melting temperature of the upper glaze
layer 30 is the same as the second melting temperature of the upper
glaze layer composition. A difference between the second melting
temperature and the first melting temperature of the upper glaze
layer 30 is the same as the difference between the second melting
temperature and the first melting temperature of the upper glaze
layer composition (upper glaze layer melting temperature
difference).
[0043] When the third melting temperature of the upper glaze layer
30 is obtained from the sanitary ware 1 including the upper glaze
layer 30, the measurement is performed by the following measurement
method 2-2.
[0044] <Measurement Method 2-2>
[0045] The powder of the upper glaze layer 30 is press-molded to
obtain a cylindrical sample. Light is radiated while heating the
obtained cylindrical sample. A light amount of the reflected light
reflected by a surface of the cylindrical sample is measured. The
earliest temperature at which the light amount of the reflected
light is ten times or more the light amount of the reflected light
detected at the beginning of glistening is taken as the third
melting temperature.
[0046] The powder of the upper glaze layer 30 may be obtained, for
example, by appropriately cutting and grinding the upper glaze
layer 30. Conditions for obtaining the cylindrical sample are the
same as the conditions for obtaining the cylindrical sample in the
above measurement method 1-2. The third melting temperature of the
upper glaze layer 30 is the same as the third melting temperature
of the upper glaze layer composition.
[0047] In the present specification, "pore" means a pore actually
contained in the upper glaze layer 30 and the intermediate layer
20. Pores can be generated, for example, due to at least one of
oxidation reactions, decomposition reactions and voids and the
like. The oxidation reactions are based on components contained in
at least one of the upper glaze layer 30, the ceramic base material
10, and an intermediate layer composition. The decomposition
reactions are based on the components contained in at least one of
the upper glaze layer 30, the ceramic base material 10, and an
intermediate layer composition. The voids are included in at least
one of the upper glaze layer 30, the ceramic base material 10, and
the intermediate layer composition. The pores are counted by
binarizing a brightness of an image using image-processing software
in the image obtained by observing a cut surface of the upper glaze
layer 30 with a microscope or the like, and determining a
relatively dark place as a pore. A size of the pores to be counted
is set to be a diameter of 2 .mu.m or more by converting the pores
in the cut surface to a perfect circle.
[0048] The pores to be counted can be determined, for example, by
the following procedure. The sanitary ware 1 is cut along a
thickness direction of the upper glaze layer 30 using a small
sample cutter. The cut surface after cutting is observed with a
microscope (DSX510, manufactured by Olympus Corporation) at a
magnification of 125 times. In the observed image, the brightness
of the image is binarized using image-processing software, and one
having a size of .pi..mu.m2 (an area equivalent to a pore of 2
.mu.m in diameter) or more in each area of a relatively dark place
is detected as a pore.
[0049] The ratio of the area of the pores to the area of the cut
surface obtained by cutting the upper glaze layer 30 along the
thickness direction (hereinafter, also referred to as a "pore area
ratio of the upper glaze layer 30") is 3% or less. The pore area
ratio of the upper glaze layer 30 may be 2.30% or less. The pore
area ratio of the upper glaze layer 30 may be 2% or less. The pore
area ratio of the upper glaze layer 30 may be 1.53% or less. The
pore area ratio of the upper glaze layer 30 may be 1.26% or less.
The pore area ratio of the upper glaze layer 30 may be 0.95% or
less. When the pore area ratio of the upper glaze layer 30 is equal
to or less than the above upper limit value (3% or less), irregular
reflection of the light incident on the upper glaze layer 30 caused
by the pores in the upper glaze layer 30 is easily inhibited. For
this reason, the "depth" of the sanitary ware 1 is more easily
improved. Similarly, when the pore area ratio of the upper glaze
layer 30 is equal to or less than the above upper limit value (3%
or less), irregular reflection of the light incident on the upper
glaze layer 30 caused by the pores in the upper glaze layer 30 is
easily inhibited. For this reason, the "beauty" of the sanitary
ware 1 is more easily improved. A lower limit value of the pore
area ratio of the upper glaze layer 30 is not particularly limited,
but is usually 0.01% or more. For example, the pore area ratio of
the upper glaze layer 30 may be 0.01% or more and 3% or less. The
pore area ratio of the upper glaze layer 30 may be 0.01% or more
and 2.30% or less. The pore area ratio of the upper glaze layer 30
may be 0.01% or more and 2% or less. The pore area ratio of the
upper glaze layer 30 may be 0.01% or more and 1.53% or less. The
pore area ratio of the upper glaze layer 30 may be 0.01% or more
and 1.26% or less. The pore area ratio of the upper glaze layer 30
may be 0.01% or more and 0.95% or less. The pore area ratio (%) of
the upper glaze layer 30 can be obtained by dividing a total area
(mm2) of the pores detected in the image observed using the
above-mentioned microscope or the like by a visual field area (mm2)
in the observed image.
[0050] The average pore size of pores in the cut surface obtained
by cutting the upper glaze layer 30 along the thickness direction
(hereinafter also referred to as an "average pore size of the upper
glaze layer 30") may be 50 .mu.m or less. The average pore size of
the upper glaze layer 30 may be 40 .mu.m or less. The average pore
size of the upper glaze layer 30 may be 30 .mu.m or less. The
average pore size of the upper glaze layer 30 may be 24 .mu.m or
less. The average pore size of the upper glaze layer 30 may be 15
.mu.m or less. When the average pore size of the upper glaze layer
30 is equal to or less than the above upper limit value (50 .mu.m
or less), irregular reflection of the light incident on the upper
glaze layer 30 caused by the pores in the upper glaze layer 30 is
easily inhibited. For this reason, the "depth" of the sanitary ware
1 is more easily improved. Similarly, when the average pore size of
the upper glaze layer 30 is equal to or less than the above upper
limit value (50 .mu.m or less), irregular reflection of the light
incident on the upper glaze layer 30 caused by the pores in the
upper glaze layer 30 is easily inhibited. For this reason, the
"beauty" of the sanitary ware 1 is more easily improved. A lower
limit value of the average pore size of the upper glaze layer 30 is
2 .mu.m. For example, the average pore size of the upper glaze
layer 30 may be 2 .mu.m or more and 50 .mu.m or less. The average
pore size of the upper glaze layer 30 may be 2 .mu.m or more to 40
.mu.m or less. The average pore size of the upper glaze layer 30
may be 2 .mu.m or more to 30 .mu.m or less. The average pore size
of the upper glaze layer 30 may be 2 .mu.m or more to 24 .mu.m or
less. The average pore size of the upper glaze layer 30 may be 2
.mu.m or more to 15 .mu.m or less. The average pore size (.mu.m) in
the upper glaze layer 30 is an average value obtained such that, in
the image observed using a microscope or the like described above,
the pore size (diameter) is calculated based on a perfect circle
converted from an area of each portion detected as a pore, and a
total of the pore sizes is divided by the number of detected pores
to obtain the average value.
[0051] The number of pores in the cut surface obtained by cutting
the upper glaze layer 30 along the thickness direction
(hereinafter, also referred to as a "number of pores in the cut
surface of the upper glaze layer 30") may be 120 or less per 1 mm2
The number of pores in the cut surface of the upper glaze layer 30
may be 100 or less per 1 mm2 The number of pores in the cut surface
of the upper glaze layer 30 may be 80 or less per 1 mm2 The number
of pores in the cut surface of the upper glaze layer 30 may be 67
or less per 1 mm2 The number of pores in the cut surface of the
upper glaze layer 30 may be 48 or less per 1 mm2 The number of
pores in the cut surface of the upper glaze layer 30 may be 27 or
less per 1 mm2 When the number of pores in the cut surface of the
upper glaze layer 30 is equal to or less than the above upper limit
value (120 or less), irregular reflection of light incident on the
upper glaze layer 30 caused by the pores in the upper glaze layer
30 is easily inhibited. For this reason, the "depth" of the
sanitary ware 1 is more easily improved. Similarly, when the number
of pores in the cut surface of the upper glaze layer 30 is equal to
or less than the above upper limit value (120 or less), irregular
reflection of light incident on the upper glaze layer 30 caused by
the pores in the upper glaze layer 30 is easily inhibited. For this
reason, the "beauty" of the sanitary ware 1 is more easily
improved. A lower limit value of the number of pores in the cut
surface of the upper glaze layer 30 is not particularly limited,
but is usually 1 or more. For example, the number of pores in the
cut surface of the upper glaze layer 30 may be 1 or more and 120 or
less per 1 mm2 The number of pores in the cut surface of the upper
glaze layer 30 may be 1 or more and 100 or less per 1 mm2 The
number of pores in the cut surface of the upper glaze layer 30 may
be 1 or more and 80 or less per 1 mm2 The number of pores in the
cut surface of the upper glaze layer 30 may be 1 or more and 67 or
less per 1 mm2 The number of pores in the cut surface of the upper
glaze layer 30 may be 1 or more and 48 or less per 1 mm2 The number
of pores in the cut surface of the upper glaze layer 30 may be 1 or
more and 27 or less per 1 mm2 The number of pores (pieces/mm2) in
the cut surface of the upper glaze layer 30 can be obtained by
dividing the number of pores detected in the image observed using
the above-described microscope or the like by a visual field area
(mm2) in the observed image.
[0052] The lower limit value of the thickness T30 of the upper
glaze layer 30 may be 100 .mu.m. The lower limit value of the
thickness T30 of the upper glaze layer 30 may be 150 .mu.m. The
lower limit value of the thickness T30 of the upper glaze layer 30
may be 200 .mu.m. The lower limit value of the thickness T30 of the
upper glaze layer 30 may be 242 .mu.m. The lower limit value of the
thickness T30 of the upper glaze layer 30 may be 253 .mu.m. The
upper limit value of the upper glaze layer 30 may be 1000 .mu.m.
The upper limit value of the upper glaze layer 30 may be 800 .mu.m.
The upper limit value of the upper glaze layer 30 may be 600 .mu.m.
The upper limit value of the upper glaze layer 30 may be 500 .mu.m.
The upper limit value of the upper glaze layer 30 may be 349 .mu.m.
For example, the range of the thickness T30 of the upper glaze
layer 30 may be 100 .mu.m or more. The range of the thickness T30
of the upper glaze layer 30 may be 100 to 1,000 .mu.m. The range of
the thickness T30 of the upper glaze layer 30 may be 150 to 800
.mu.m. The range of the thickness T30 of the upper glaze layer 30
may be 200 to 600 .mu.m. The range of the thickness T30 of the
upper glaze layer 30 may be 242 to 500 .mu.m. The range of the
thickness T30 of the upper glaze layer 30 may be 253 to 349 .mu.m.
When the thickness T30 is equal to or more than the above lower
limit value (100 .mu.m or more), the surface of the upper glaze
layer 30 is easily flattened. When the thickness T30 is equal to or
less than the above upper limit value (1,000 .mu.m or less), the
bubbles in the upper glaze layer composition are easily discharged
outside of the upper glaze layer 30.
[0053] The thickness T30 of the upper glaze layer 30 can be
determined, for example, by the following procedure. The sanitary
ware 1 is cut along the thickness direction of the upper glaze
layer 30 using a small sample cutter. The cut surface after cutting
is observed with a microscope (DSX510, manufactured by Olympus
Corporation) at a magnification of 125 times. In the observed
image, the distance between a boundary line (also referred to as an
upper-intermediate boundary line) between the upper glaze layer 30
and the intermediate layer 20 and the surface of the upper glaze
layer 30 is measured at any 20 places. An arithmetic average value
of the measured distances is taken as the thickness T30 of the
upper glaze layer 30. The portions at which the sanitary ware 1 is
cut are not particularly limited, and portions easily seen by the
human eye are preferable. Examples of the portions easily seen by
the human eye include a bowl surface of a washbowl, a top surface
of a washbowl, a top surface of a urinal, a rim portion of a toilet
bowl, a bowl surface of a toilet bowl, a side surface of a toilet
bowl and the like.
[0054] The difference T30.DELTA. between the maximum value T30MAX
of the thickness T30 of the upper glaze layer 30 and the minimum
value T30MIN of the thickness T30 of the upper glaze layer 30 may
be 70 .mu.m or less. The difference T30.DELTA. may be 50 .mu.m or
less. The difference T30.DELTA. may be 40 .mu.m or less. The
difference T30.DELTA. may be 30 .mu.m or less. When the difference
T30.DELTA. is equal to or less than the above upper limit value (70
.mu.m or less), irregular reflection of the light at an interface
between the upper glaze layer 30 and the intermediate layer 20 is
easily inhibited. As a result, the "depth" of the sanitary ware 1
is more easily improved. Similarly, when the difference T30.DELTA.
is equal to or less than the above upper limit value (70 .mu.m or
less), irregular reflection of the light at the interface between
the upper glaze layer 30 and the intermediate layer 20 is easily
inhibited. As a result, the "beauty" of the sanitary ware 1 is more
easily improved. A lower limit value of the difference T30.DELTA.
is not particularly limited, but is usually 0.1 .mu.m or more. For
example, the difference T30.DELTA. may be 0.1 .mu.m or more and 70
.mu.m or less. The difference T30.DELTA. may be 0.1 .mu.m or more
and 50 .mu.m or less. The difference T30.DELTA. may be 0.1 .mu.m or
more to 40 .mu.m or less. The difference T30.DELTA. may be 0.1
.mu.m or more and 30 .mu.m or less.
[0055] A ratio of the difference T30.DELTA. to the thickness T30
(hereinafter also referred to as a "T30.DELTA./T30 ratio") may be
25% or less. The T30.DELTA./T30 ratio may be 20% or less. The
T30.DELTA./T30 ratio may be 10% or less. When the T30.DELTA./T30
ratio is equal to or less than the upper limit value (25% or less),
irregular reflection of the light at the interface between the
upper glaze layer 30 and the intermediate layer 20 is easily
inhibited. As a result, the "depth" of the sanitary ware 1 is more
easily improved. Similarly, when the T30.DELTA./T30 ratio is equal
to or less than the upper limit value (25% or less), irregular
reflection of the light at the interface between the upper glaze
layer 30 and the intermediate layer 20 is easily inhibited. As a
result, the "beauty" of the sanitary ware 1 is more easily
improved. A lower limit value of the T30.DELTA./T30 ratio is not
particularly limited, but is usually 0.01% or more. For example,
the range of the T30.DELTA./T30 ratio may be 0.01% or more and 25%
or less. The range of the T30.DELTA./T30 ratio may be 0.01% or more
and 20% or less. The range of the T30.DELTA./T30 ratio may be 0.01%
or more and 10% or less.
[0056] The maximum value T30MAX of the thickness T30 and the
minimum value T30MIN of the thickness T30 can be obtained, for
example, by the following procedure. Similarly to the procedure for
determining the thickness T30 of the upper glaze layer 30, the
distance between the surfaces of the upper glaze layer 30 and the
upper-intermediate boundary line is measured at any 20 places.
Among the 20 measured places, one place with the largest distance
between the surface of the upper glaze layer 30 and the
upper-intermediate boundary line is taken as the maximum value
T30MAX. Among the 20 measured places, one place with the smallest
distance between the surface of the upper glaze layer 30 and the
upper-intermediate boundary line is taken as the minimum value
T30MIN.
[0057] The difference T30.DELTA. can be controlled by flattening
the interface between the upper glaze layer 30 and the intermediate
layer 20. A smoothness of the interface between the upper glaze
layer 30 and the intermediate layer 20 can be controlled by the
melting start temperature of the intermediate layer composition
which will be described later, the average pore size at the cut
surface obtained by cutting the intermediate layer 20 along the
thickness direction, the ratio of the pore area to the area of the
cut surface obtained by cutting the intermediate layer 20 along the
thickness direction, and combinations thereof.
[0058] The intermediate layer 20 is a fired material of an
intermediate layer composition. The intermediate layer 20 is a
layer including a glaze positioned between the ceramic base
material 10 and the upper glaze layer 30. The intermediate layer
composition is a slurry (a sludge) in which a raw material
(intermediate layer raw material) for forming the intermediate
layer 20 is dispersed in water. The range of the content of water
relative to the total mass of the intermediate layer
composition-may be 40 to 60 mass %. The range of the content of
water relative to the total mass of the intermediate layer
composition may be 40 to 50 mass %.
[0059] The average particle size of the solid content contained in
the intermediate layer composition may be 10 .mu.m or less. The
average particle size of the solid content contained in the
intermediate layer composition may be 8 .mu.m or less. The average
particle size of the solid content contained in the intermediate
layer composition may be 6 .mu.m or less. When the average particle
size of the solid content contained in the intermediate layer
composition is equal to or less than the above upper limit value
(10 .mu.m or less), the melting start temperature of the solid
content contained in the intermediate layer composition is easily
lowered. A lower limit value of the average particle size of the
solid content contained in the intermediate layer composition is
not particularly limited, and is, for example, 0.05 .mu.m or more.
For example, the range of the average particle size of the solid
content contained in the intermediate layer composition may be 0.05
.mu.m or more and 10 .mu.m or less. The range of the average
particle size of the solid content contained in the intermediate
layer composition may be 0.05 .mu.m or more and 8 .mu.m or less.
The range of the average particle size of the solid content
contained in the intermediate layer composition may be 0.05 .mu.m
or more and 6 .mu.m or less. The average particle size of the solid
content contained in the intermediate layer composition can be
adjusted, for example, by grinding the intermediate layer raw
material. For example, a ball mill can be exemplified as a tool for
grinding intermediate layer raw materials.
[0060] The average particle size of the solid content contained in
the intermediate layer composition can be measured by the same
method as the average particle size of the solid content contained
in the upper glaze layer composition. The solid content contained
in the intermediate layer composition is dried materials of the
intermediate layer composition.
[0061] Examples of the intermediate layer composition include a
composition containing 50 to 80 mass % of SiO2, 5 to 40 mass % of
Al2O3, and 5 to 30 mass % of a total of Na2O, K2O, CaO, MgO and ZnO
with respect to the total mass of the solid content contained in
the intermediate layer composition. A total of the content of each
component of the solid content contained in the intermediate layer
composition is adjusted such that it does not exceed 100 mass %
with respect to the total mass of the solid content contained in
the intermediate layer composition.
[0062] A composition of the intermediate layer composition may
include 2 to 16 moles of SiO2 and 0 to 5 moles of Al2O3 as a molar
ratio when the sum of the number of moles of Na2O, K2O, CaO, MgO,
and ZnO is set to 1.
[0063] The intermediate layer composition may contain a frit. The
range of the content of the frit relative to the total mass of the
solid content contained in the intermediate layer composition may
be 0 to 30 mass %. The range of the content of the frit relative to
the total mass of the solid content contained in the intermediate
layer composition may be 0 to 20 mass %.
[0064] The dried materials of the intermediate layer composition
(hereinafter also referred to as the intermediate layer raw
material) may be a mixture of the dried materials of the ceramic
base material composition (hereinafter also referred to as the
ceramic base raw material) and the dried materials of the upper
glaze layer composition (hereinafter referred to as the glaze raw
material). When the intermediate layer raw material is a mixture of
the ceramic base raw material and the glaze raw material, a mass
ratio represented by the ceramic base raw material/the glaze raw
material (hereinafter also referred to as a "ceramic base/glaze
ratio") may be 20/80 to 80/20. The ceramic base/glaze ratio may be
30/70 to 70/30. The ceramic base/glaze ratio may be 40/60 to 60/40.
When the ceramic base/glaze ratio is equal to or more than the
above lower limit value (20/80 or more), adhesion between the
ceramic base material 10 and the intermediate layer 20 is easily
increased. When the ceramic base/glaze ratio is equal to or less
than the above upper limit value (80/20 or less), the interface
between the intermediate layer 20 and the upper glaze layer 30 is
easily flattened. From the viewpoint of further improving at least
one of the "depth" and the "beauty" of the sanitary ware 1, the
intermediate layer raw material may be a mixture of the ceramic
base raw material and the glaze raw material. The intermediate
layer composition may be a mixture of the ceramic base material
composition and the upper glaze layer composition which are mixed
together to have the above ceramic base/glaze ratio.
[0065] The intermediate layer composition may include a pigment. In
some embodiments, the intermediate layer composition contains the
pigment so that the intermediate layer 20 is capable of being
colored. By coloring the intermediate layer 20, the color of the
ceramic base material 10 is capable of being concealed. By
concealing the color of the ceramic base material 10, the "beauty"
of the sanitary ware 1 is more easily improved. Examples of the
pigment include zirconium silicate, aluminum oxide and the like.
When the intermediate layer composition contains the pigment, the
range of the content of the pigment relative to the total mass of
the solid content contained in the intermediate layer composition
may be 3 to 15 mass %. The range of the content of the pigment
relative to the total mass of the solid content contained in the
intermediate layer composition may be 6 to 15 mass %.
[0066] The melting start temperature of the intermediate layer
composition can be defined by any of the first melting temperature
and the second melting temperature. The lower limit value of the
first melting temperature of the intermediate layer composition may
be 850.degree. C. The lower limit value of the first melting
temperature of the intermediate layer composition may be
910.degree. C. The lower limit value of the first melting
temperature of the intermediate layer composition may be
930.degree. C. The upper limit value of the first melting
temperature of the intermediate layer composition may be
960.degree. C. The upper limit value of the first melting
temperature of the intermediate layer composition may be
950.degree. C. For example, the range of the first melting
temperature of the intermediate layer composition may be 850 to
960.degree. C. The range of the first melting temperature of the
intermediate layer composition may be 910 to 950.degree. C. The
range of the first melting temperature of the intermediate layer
composition may be 930 to 950.degree. C. When the first melting
temperature of the intermediate layer composition is equal to or
higher than the above lower limit value (850.degree. C. or more),
generation of bubbles when firing the intermediate layer
composition is easily inhibited. When the first melting temperature
of the intermediate layer composition is equal to or less than the
above upper limit value (960.degree. C. or less), the interface
between the upper glaze layer 30 and the intermediate layer 20 is
easily flattened. The first melting temperature of the intermediate
layer composition can be measured in the same method as the first
melting temperature of the upper glaze layer composition.
[0067] The lower limit value of the difference in temperature
between the first melting temperature of the upper glaze layer
composition and the first melting temperature of the intermediate
layer composition (also referred to as a first temperature
difference) may be 10.degree. C. The lower limit value of the first
temperature difference may be 30.degree. C. The lower limit value
of the first temperature difference may be 60.degree. C. The upper
limit value of the first temperature difference may be 120.degree.
C. The upper limit value of the first temperature difference may be
115.degree. C. The upper limit value of the first temperature
difference may be 110.degree. C. For example, the range of the
first temperature difference may be 10 to 120.degree. C. The range
of the first temperature difference may be 30 to 115.degree. C. The
range of the first temperature difference may be 60 to 110.degree.
C. When the first temperature difference is within the above
numerical range (10.degree. C. or more and 120.degree. C. or less),
the interface between the upper glaze layer 30 and the intermediate
layer 20 is easily flattened. As a result, irregular reflection of
the light at the interface between the upper glaze layer 30 and the
intermediate layer 20 is capable of being inhibited so that the
"depth" of the sanitary ware 1 is more easily improved. Similarly,
when the first temperature difference is within the above numerical
range (10.degree. C. or more and 120.degree. C. or less), the
interface between the upper glaze layer 30 and the intermediate
layer 20 is easily flattened. As a result, irregular reflection of
the light at the interface between the upper glaze layer 30 and the
intermediate layer 20 is capable of being inhibited so that the
"beauty" of the sanitary ware 1 is more easily improved.
[0068] The lower limit value of the second melting temperature of
the intermediate layer composition may be 1,090.degree. C. The
lower limit value of the second melting temperature of the
intermediate layer composition may be 1,095.degree. C. The lower
limit value of the second melting temperature of the intermediate
layer composition may be 1,100.degree. C. The upper limit value of
the second melting temperature of the intermediate layer
composition may be 1,230.degree. C. The upper limit value of the
second melting temperature of the intermediate layer composition
may be 1,225.degree. C. The upper limit value of the second melting
temperature of the intermediate layer composition may be
1,220.degree. C. For example, the range of the second melting
temperature of the intermediate layer composition may be 1,090 to
1,230.degree. C. The range of the second melting temperature of the
intermediate layer composition may be 1,095 to 1,225.degree. C. The
range of the second melting temperature of the intermediate layer
composition may be 1,100 to 1,220.degree. C. When the second
melting temperature of the intermediate layer composition is equal
to or higher than the above lower limit value (1,090.degree. C. or
more), generation of bubbles when firing the intermediate layer
composition is easily inhibited. When the second melting
temperature of the intermediate layer composition is equal to or
less than the above upper limit value (1,230.degree. C. or less),
the interface between the upper glaze layer 30 and the intermediate
layer 20 is easily flattened. The second melting temperature of the
intermediate layer composition can be measured in the same method
as the second melting temperature of the upper glaze layer
composition.
[0069] The lower limit value of the difference in temperature
between the second melting temperature of the upper glaze layer
composition and the second melting temperature of the intermediate
layer composition (also referred to as a second temperature
difference) may be 10.degree. C. The lower limit value of the
second temperature difference may be 100.degree. C. The lower limit
value of the second temperature difference may be 200.degree. C.
The upper limit value of the second temperature difference may be
330.degree. C. The upper limit value of the second temperature
difference may be 325.degree. C. The upper limit value of the
second temperature difference may be 320.degree. C. For example,
the range of the second temperature difference may be 10 to
330.degree. C. The range of the second temperature difference may
be 100 to 325.degree. C. The range of the second temperature
difference may be 200 to 320.degree. C. When the second temperature
difference is within the above numerical range (10.degree. C. or
more and 330.degree. C. or less), the interface between the upper
glaze layer 30 and the intermediate layer 20 is easily flattened.
As a result, irregular reflection of the light at the interface
between the upper glaze layer 30 and the intermediate layer 20 is
capable of being inhibited so that the "depth" of the sanitary ware
1 is more easily improved. Similarly, when the second temperature
difference is within the above numerical range (10.degree. C. or
more and 330.degree. C. or less), the interface between the upper
glaze layer 30 and the intermediate layer 20 is easily flattened.
As a result, irregular reflection of the light at the interface
between the upper glaze layer 30 and the intermediate layer 20 is
capable of being inhibited so that the "beauty" of the sanitary
ware 1 is more easily improved.
[0070] The lower limit value of the difference between the second
melting temperature and the first melting temperature of the
intermediate layer composition (an intermediate layer melting
temperature difference) may be 50.degree. C. The lower limit value
of the intermediate layer melting temperature difference may be
100.degree. C. The lower limit value of the intermediate layer
melting temperature difference may be 230.degree. C. The upper
limit value of the intermediate layer melting temperature
difference may be 300.degree. C. For example, the range of the
intermediate layer melting temperature difference may be 50 to
300.degree. C. The range of the intermediate layer melting
temperature difference may be 100 to 300.degree. C. The range of
the intermediate layer melting temperature difference may be 230 to
300.degree. C. When the intermediate layer melting temperature
difference is equal to or higher than the above lower limit value
(50.degree. C. or more), the average pore size of pores generated
when firing the intermediate layer composition is easily reduced.
When the intermediate layer melting temperature difference is equal
to or less than the above upper limit value (300.degree. C. or
less), generation of bubbles when firing the intermediate layer
composition is easily inhibited. The intermediate layer melting
temperature difference is determined by subtracting the first
melting temperature of the intermediate layer composition from the
second melting temperature of the intermediate layer
composition.
[0071] The first melting temperature of the intermediate layer
composition can be adjusted on the basis of a type of intermediate
layer raw material, a blending proportion of the intermediate layer
raw material, the average particle size of the solid content of the
intermediate layer composition, and combinations thereof. The
second melting temperature of the intermediate layer composition
can be adjusted similarly to the first melting temperature of the
intermediate layer composition.
[0072] When obtaining the melting start temperature of the
intermediate layer 20 from the sanitary ware 1 including the
intermediate layer 20, the first melting temperature and the second
melting temperature are measured, using the powder of the
intermediate layer 20 as a sample powder, on the basis of the same
method as the measurement method 2-1. The powder of the
intermediate layer 20 is obtained, for example, by appropriately
cutting and grinding the intermediate layer 20. The first melting
temperature of the intermediate layer 20 is the same as the first
melting temperature of the intermediate layer composition. The
second melting temperature of the intermediate layer 20 is the same
as the second melting temperature of the intermediate layer
composition. The difference between the second melting temperature
and the first melting temperature of the intermediate layer 20 is
the same as the difference between the second melting temperature
and the first melting temperature of the intermediate layer
composition (intermediate layer melting temperature
difference).
[0073] A ratio of the area of the pores to the area of the cut
surface obtained by cutting the intermediate layer 20 along the
thickness direction (hereinafter, also referred to as a "pore area
ratio of the intermediate layer 20") may be 20% or less. The pore
area ratio of the intermediate layer 20 may be 15% or less. The
pore area ratio of the intermediate layer 20 may be 12% or less.
The pore area ratio of the intermediate layer 20 may be 11.36% or
less. The pore area ratio of the intermediate layer 20 may be 9.75%
or less. When the pore area ratio of the intermediate layer 20 is
equal to or less than the above upper limit value (20% or less),
irregular reflection of the light incident on the upper glaze layer
30 caused by the pores in the intermediate layer 20 is easily
inhibited. As a result, the irregular reflection of the light at
the interface between the upper glaze layer 30 and the intermediate
layer 20 is capable of being inhibited so that the "depth" of the
sanitary ware 1 is more easily improved. Similarly, when the pore
area ratio of the intermediate layer 20 is equal to or less than
the above upper limit value (20% or less), irregular reflection of
the light incident on the upper glaze layer 30 caused by the pores
in the intermediate layer 20 is easily inhibited. As a result, the
irregular reflection of the light at the interface between the
upper glaze layer 30 and the intermediate layer 20 is capable of
being inhibited so that the "beauty" of the sanitary ware 1 is more
easily improved. A lower limit value of the pore area ratio of the
intermediate layer 20 is not particularly limited, but is usually
1.0% or more. For example, the range of the pore area ratio of the
intermediate layer 20 may be 1.0% or more and 20% or less. The
range of the pore area ratio of the intermediate layer 20 may be
1.0% or more and 15% or less. The range of the pore area ratio of
the intermediate layer 20 may be 1.0% or more and 12% or less. The
range of the pore area ratio of the intermediate layer 20 may be
1.0% or more and 11.36% or less. The range of the pore area ratio
of the intermediate layer 20 may be 1.0% or more and 9.75% or less.
The pore area ratio of the intermediate layer 20 is determined by
the same method as the pore area ratio of the upper glaze layer
30.
[0074] The average pore size of pores in the cut surface obtained
by cutting the intermediate layer 20 along the thickness direction
(hereinafter also referred to as an "average pore size of the
intermediate layer 20") may be 25 .mu.m or less. The average pore
size of the intermediate layer 20 may be 20 .mu.m or less. The
average pore size of the intermediate layer 20 may be 15 .mu.m or
less. The average pore size of the intermediate layer 20 may be 14
.mu.m or less. The average pore size of the intermediate layer 20
may be 13 .mu.m or less. When the average pore size of the
intermediate layer 20 is equal to or less than the upper limit
value (25 .mu.m or less), irregular reflection of the light
incident on the upper glaze layer 30 caused by the pores in the
intermediate layer 20 is easily inhibited. As a result, the
irregular reflection of the light at the interface between the
upper glaze layer 30 and the intermediate layer 20 is capable of
being inhibited so that the "depth" of the sanitary ware 1 is more
easily improved. Similarly, when the average pore size of the
intermediate layer 20 is equal to or less than the upper limit
value (25 .mu.m or less), irregular reflection of the light
incident on the upper glaze layer 30 caused by the pores in the
intermediate layer 20 is easily inhibited. As a result, the
irregular reflection of the light at the interface between the
upper glaze layer 30 and the intermediate layer 20 is capable of
being inhibited so that the "beauty" of the sanitary ware 1 is more
easily improved. A lower limit value of the average pore size of
the intermediate layer 20 may be 2 .mu.m. For example, the range of
the average pore size of the intermediate layer 20 may be 2 .mu.m
or more and 25 .mu.m or less. The range of the average pore size of
the intermediate layer 20 may be 2 .mu.m or more and 20 .mu.m or
less. The range of the average pore size of the intermediate layer
20 may be 2 .mu.m or more and 15 .mu.m or less. The range of the
average pore size of the intermediate layer 20 may be 2 .mu.m or
more and 14 .mu.m or less. The range of the average pore size of
the intermediate layer 20 may be 2 .mu.m or more and 13 .mu.m or
less. The average pore size of the intermediate layer 20 is
determined by the same method as the average pore size of pores in
the cut surface of the upper glaze layer 30.
[0075] A number of pores in the cut surface obtained by cutting the
intermediate layer 20 along the thickness direction (hereinafter,
also referred to as a "number of pores in the cut surface of the
intermediate layer 20") may be 1,000 or less per 1 mm2 The number
of pores in the cut surface of the intermediate layer 20 may be 700
or less per 1 mm2 The number of pores in the cut surface of the
intermediate layer 20 may be 500 or less per 1 mm2 The number of
pores in the cut surface of the intermediate layer 20 may be 443 or
less per 1 mm2 The number of pores in the cut surface of the
intermediate layer 20 may be 419 or less per 1 mm2 When the number
of pores in the cut surface of the intermediate layer 20 is equal
to or less than the above upper limit value (1,000 or less),
irregular reflection of the light incident on the upper glaze layer
30 caused by the pores in the intermediate layer 20 is easily
inhibited. As a result, the irregular reflection of the light at
the interface between the upper glaze layer 30 and the intermediate
layer 20 is capable of being inhibited so that the "depth" of the
sanitary ware 1 is more easily improved. Similarly, when the number
of pores in the cut surface of the intermediate layer 20 is equal
to or less than the above upper limit value (1,000 or less),
irregular reflection of the light incident on the upper glaze layer
30 caused by the pores in the intermediate layer 20 is easily
inhibited. As a result, the irregular reflection of the light at
the interface between the upper glaze layer 30 and the intermediate
layer 20 is capable of being inhibited so that the "beauty" of the
sanitary ware 1 is more easily improved. A lower limit value of the
number of pores in the cut surface of the intermediate layer 20 is
not particularly limited, but is usually 1 or more. The lower limit
value of the number of pores in the cut surface of the intermediate
layer 20 may be 189 or more per 1 mm2 The lower limit value of the
number of pores in the cut surface of the intermediate layer 20 may
be 269 or more per 1 mm2 For example, the range of the number of
pores in the cut surface of the intermediate layer 20 may be 1 or
more and 1,000 or less per 1 mm2 The range of the number of pores
in the cut surface of the intermediate layer 20 may be 1 or more
and 700 or less per 1 mm2 The range of the number of pores in the
cut surface of the intermediate layer 20 may be 1 or more and 500
or less per 1 mm2 The range of the number of pores in the cut
surface of the intermediate layer 20 may be 189 or more and 443 or
less per 1 mm2 The range of the number of pores in the cut surface
of the intermediate layer 20 may be 269 or more and 419 or less per
1 mm2 The number of pores in the cut surface of the intermediate
layer 20 can be counted by the same method as the number of pores
in the cut surface of the upper glaze layer 30.
[0076] The lower limit value of the thickness T20 of the
intermediate layer 20 may be 200 .mu.m. The lower limit value of
the thickness T20 of the intermediate layer 20 may be 250 .mu.m.
The lower limit value of the thickness T20 of the intermediate
layer 20 may be 300 .mu.m. The lower limit value of the thickness
T20 of the intermediate layer 20 may be 494 .mu.m. The lower limit
value of the thickness T20 of the intermediate layer 20 may be 508
.mu.m. The upper limit value of the thickness T20 of the
intermediate layer 20 may be 1000 .mu.m. The upper limit value of
the thickness T20 of the intermediate layer 20 may be 800 .mu.m.
The upper limit value of the thickness T20 of the intermediate
layer may be 600 .mu.m. The upper limit value of the thickness T20
of the intermediate layer 20 may be 575 .mu.m. The upper limit
value of the thickness T20 of the intermediate layer 20 may be 558
.mu.m. For example, the range of the thickness T20 of the
intermediate layer 20 may be 200 .mu.m or more. The range of the
thickness T20 of the intermediate layer 20 may be 200 to 1,000
.mu.m. The range of the thickness T20 of the intermediate layer 20
may be 250 to 800 .mu.m. The range of the thickness T20 of the
intermediate layer 20 may be 300 to 600 .mu.m. The range of the
thickness T20 of the intermediate layer 20 may be 494 to 575 .mu.m.
The range of the thickness T20 of the intermediate layer 20 may be
508 to 558 .mu.m. When the thickness T20 is equal to or more than
the above lower limit value (200 .mu.m or more), the interface
between the intermediate layer 20 and the upper glaze layer 30 is
easily flattened. When the thickness T20 is equal to or less than
the above upper limit value (1,000 .mu.m or less), the bubbles in
the intermediate layer composition are easily discharged outside of
the intermediate layer 20.
[0077] The thickness T20 of the intermediate layer 20 can be
determined, for example, by the following procedure. The sanitary
ware 1 is cut along the thickness direction of the intermediate
layer 20 using a small sample cutter. The cut surface after cutting
is observed with a microscope (DSX510, manufactured by Olympus
Corporation) at a magnification of 125 times. In the observed
image, a distance between the boundary line between the upper glaze
layer 30 and the intermediate layer 20 (upper-intermediate boundary
line) and a boundary line between the intermediate layer 20 and the
ceramic base material 10 (an intermediate-base material boundary
line) is measured at any 20 places. An arithmetic average value of
the measured distances is taken as the thickness T20 of the
intermediate layer 20.
[0078] A difference T20.DELTA. between the maximum value T20MAX of
the thickness T20 of the intermediate layer 20 and the minimum
value T20MIN of the thickness T20 of the intermediate layer 20 may
be 50 .mu.m or less. The difference T20.DELTA. may be 40 .mu.m or
less. The difference T20.DELTA. may be 30 .mu.m or less. When the
difference T20.DELTA. is equal to or less than the above upper
limit value (50 .mu.m or less), irregular reflection of the light
at the interface between the upper glaze layer 30 and the
intermediate layer 20 is easily inhibited. As a result, the "depth"
of the sanitary ware 1 is more easily improved. Similarly, when the
difference T20.DELTA. is equal to or less than the above upper
limit value (50 .mu.m or less), irregular reflection of the light
at the interface between the upper glaze layer 30 and the
intermediate layer 20 is easily inhibited. As a result, the
"beauty" of the sanitary ware 1 is more easily improved. A lower
limit value of the difference T20.DELTA. is not particularly
limited, but is usually 0.1 .mu.m or more. For example, the range
of the difference T20.DELTA. may be 0.1 .mu.m or more and 50 .mu.m
or less. The range of the difference T20.DELTA. may be 0.1 .mu.m or
more and 40 .mu.m or less. The range of the difference T20.DELTA.
may be 0.1 .mu.m or more and 30 .mu.m or less.
[0079] A ratio of the difference T20.DELTA. relative to the
thickness T20 (hereinafter also referred to as a "T20.DELTA./T20
ratio") may be 25% or less. The T20.DELTA./T20 ratio may be 20% or
less. The T20.DELTA./T20 ratio may be 10% or less. When the
T20.DELTA./T20 ratio is equal to or less than the upper limit value
(25% or less), irregular reflection of the light at the interface
between the upper glaze layer 30 and the intermediate layer 20 is
easily inhibited. As a result, the "depth" of the sanitary ware 1
is more easily improved. Similarly, when the T20.DELTA./T20 ratio
is equal to or less than the upper limit value (25% or less),
irregular reflection of the light at the interface between the
upper glaze layer 30 and the intermediate layer 20 is easily
inhibited. As a result, the "beauty" of the sanitary ware 1 is more
easily improved. A lower limit value of the T20.DELTA./T20 ratio is
not particularly limited, but is usually 0.01% or more. For
example, the range of the T20.DELTA./T20 ratio may be 0.01% or more
and 25% or less. The range of the T20.DELTA./T20 ratio may be 0.01%
or more and 20% or less. The range of the T20.DELTA./T20 ratio may
be 0.01% or more and 10% or less.
[0080] The maximum value T20MAX of the thickness T20 and the
minimum value T20MIN of the thickness T20 can be obtained, for
example, by the following procedure. Similarly to the procedure for
determining the thickness T20 of the intermediate layer 20, the
distance between the upper-intermediate boundary line and the
intermediate-base material boundary line is measured at any 20
places. Among the 20 measured places, one place with the largest
distance between the upper-intermediate boundary line and the
intermediate-base material boundary line is taken as the maximum
value T20MAX. Among the 20 measured places, one place with the
smallest distance between the upper-intermediate boundary and the
intermediate-base material boundary line is taken as the minimum
value T20MIN.
[0081] [Method of Manufacturing Sanitary Ware]
[0082] Next, a method of manufacturing the sanitary ware 1 of the
present embodiment will be described. First, a ceramic base
material 10 is prepared. The ceramic base material 10 may not be
only a molded product obtained by molding the ceramic base material
composition, but may also be a molded product obtained by firing
and molding the ceramic base material composition. The ceramic base
material 10 may be a commercial product which has been molded in
advance. The ceramic base material 10 may be a commercial product
which has been molded and fired in advance. In the case of firing
the ceramic base material composition, the lower limit value of the
firing temperature may be 1,100.degree. C. The lower limit value of
the firing temperature may be 1,150.degree. C. The upper limit
value of the firing temperature may be 1,300.degree. C. The upper
limit value of the firing temperature may be 1,250.degree. C. For
example, the range of the firing temperature may be 1,100 to
1,300.degree. C. The range of the firing temperature may be 1,150
to 1,250.degree. C. When the firing temperature is equal to or
higher than the above lower limit value (1,100.degree. C. or more),
the strength of the ceramic base material 10 is easily increased.
When the firing temperature is equal to or less than the above
upper limit value (1,300.degree. C. or less), deformation of the
ceramic base material 10 is easily inhibited.
[0083] Next, the intermediate layer composition is applied to the
surface of the ceramic base material 10. A method of applying the
intermediate layer composition to the surface of the ceramic base
material 10 is not particularly limited, and a general method such
as dipping, pouring, spraying, or applying can be appropriately
selected. From the viewpoint of securing the thickness of the
intermediate layer 20, the method of applying the intermediate
layer composition to the surface of the ceramic base material 10
may be any of dipping, pouring, applying, and spraying. From the
viewpoint of easily making the thickness of the intermediate layer
20 uniform, the spraying is preferable as the method of applying
the intermediate layer composition to the surface of the ceramic
base material 10. A dip coating method can be exemplified for the
dipping. A spray coating method can be exemplified for the
spraying.
[0084] The amount of the intermediate layer composition applied is
not particularly limited, and may be adjusted so that the thickness
of the intermediate layer 20 after firing can be 200 .mu.m or more.
The amount of the intermediate layer composition applied can be
adjusted by appropriately adjusting the content of water in the
intermediate layer composition, a viscosity of the intermediate
layer composition, the average particle size of the solid content
contained in the intermediate layer composition, and the like. By
applying the intermediate layer composition to the surface of the
ceramic base material 10, a primary coated body is obtained.
[0085] By drying the primary coated body, it becomes easy to apply
the upper glaze layer composition to the surface of the primary
coated body. For this reason, the primary coated body may be dried.
The lower limit value of the temperature at the time of drying the
primary coated body may be 20.degree. C. The lower limit value of
the temperature at the time of drying the primary coated body may
be 30.degree. C. The lower limit value of the temperature at the
time of drying the primary coated body may be 40.degree. C. The
upper limit value of the temperature at the time of drying the
primary coated body may be 110.degree. C. The upper limit value of
the temperature at the time of drying the primary coated body may
be 100.degree. C. The upper limit value of the temperature at the
time of drying the primary coated body may be 90.degree. C. For
example, the range of the temperature at the time of drying the
primary coated body may be 20 to 110.degree. C. The range of the
temperature at the time of drying the primary coated body may be 30
to 100.degree. C. The range of the temperature at the time of
drying the primary coated body may be 40 to 90.degree. C. When the
temperature at the time of drying the primary coated body is equal
to or higher than the above lower limit value (20.degree. C. or
more), the content of water in the intermediate layer composition
is easily reduced. When the temperature at the time of drying the
primary coated body is equal to or less than the above upper limit
value (110.degree. C. or less), the surface of the intermediate
layer 20 is easily flattened. A time for drying the primary coated
body may be 0.5 to 48 hours. When the time for drying the primary
coated body is equal to or more than the above lower limit value
(0.5 hours or more), the intermediate layer composition is easily
and sufficiently dried. When the time for drying the primary coated
body is equal to or less than the above upper limit value (48 hours
or less), productivity of the sanitary ware 1 is easily
improved.
[0086] Next, the upper glaze layer composition is applied to the
surface of the primary coated body. From the viewpoint of making it
easy to adjust the thickness of the upper glaze layer 30, the
method of applying the upper glaze layer composition may be
spraying (also referred to as spray coating).
[0087] The amount of the upper glaze layer composition applied is
not particularly limited, and may be adjusted so that the thickness
of the upper glaze layer 30 after firing can be 100 .mu.m or more.
The amount of the upper glaze layer composition applied may be
adjusted by appropriately adjusting the content of water in the
upper glaze layer composition, the viscosity of the upper glaze
layer composition, the average particle size of the solid content
contained in the upper glaze layer composition, etc. By applying
the upper glaze layer composition to the surface of the primary
coated body, a secondary coated body is obtained.
[0088] Next, the secondary coated body is fired. As a firing
temperature at the time of firing the secondary coated body, a
temperature at which the ceramic base material 10 is sintered and
the intermediate layer composition and the upper glaze layer
composition are softened is preferable. The lower limit value of
the firing temperature at the time of firing the secondary coated
body may be 1,100.degree. C. The lower limit value of the firing
temperature at the time of firing the secondary coated body may be
1,150.degree. C. The upper limit value of the firing temperature at
the time of firing the secondary coated body may be 1,300.degree.
C. The upper limit value of the firing temperature at the time of
firing the secondary coated body may be 1,250.degree. C. For
example, the range of the firing temperature at the time of firing
the secondary coated body may be 1,100 to 1,300.degree. C. The
range of the firing temperature at the time of firing the secondary
coated body may be 1,150 to 1,250.degree. C. When the firing
temperature at the time of firing the secondary coated body is
equal to or higher than the above lower limit value (1,100.degree.
C. or more), the upper glaze layer composition is easily and
sufficiently melted. In addition, when the firing temperature at
the time of firing the second coated body is equal to or higher
than the above lower limit value (1,100.degree. C. or more), the
intermediate layer composition is easily and sufficiently melted.
When the firing temperature at the time of firing the secondary
coated body is equal to or less than the above upper limit value
(1,300.degree. C. or less), the surface of the upper glaze layer 30
is easily flattened. In addition, when the firing temperature at
the time of firing the second coated body is equal to or less than
the above upper limit value or less (1,300.degree. C. or less), the
interface between the intermediate layer 20 and the upper glaze
layer 30 is easily flattened.
[0089] The lower limit value of the firing time for firing the
secondary coated body may be 1 hour. The lower limit value of the
firing time for firing the secondary coated body may be 2 hours.
The lower limit value of the firing time for firing the secondary
coated body may be 3 hours. The upper limit value of the firing
time for firing the secondary coated body may be 168 hours. The
upper limit value of the firing time for firing the secondary
coated body may be 72 hours. The upper limit value of the firing
time for firing the secondary coated body may be 24 hours. For
example, the range of the firing time for firing the secondary
coated body may be 1 to 168 hours. The range of the firing time for
firing the secondary coated body may be 2 to 72 hours. The range of
the firing time for firing the secondary coated body may be 3 to 24
hours. When the firing time for firing the secondary coated body is
equal to or more than the above lower limit value (1 hour or more),
the surface of the upper glaze layer 30 is easily flattened. In
addition, when the firing time for firing the second coated body is
equal to or more than the above lower limit value (1 hour or more),
the interface between the intermediate layer 20 and the upper glaze
layer 30 is easily flattened. When the firing time for firing the
secondary coated body is equal to or less than the above upper
limit value (168 hours or less), productivity of the sanitary ware
1 is easily improved.
[0090] A fired product is obtained by firing the second coated
body. The fired product is cooled to be the sanitary ware 1. The
sanitary ware 1 may be obtained by naturally cooling the fired
product, or may be obtained by cooling such as blowing air. The
lower limit value of the temperature at the time of cooling the
fired product may be 800.degree. C. The lower limit value of the
temperature at the time of cooling the fired product may be
900.degree. C. The upper limit value of the temperature at the time
of cooling the fired product may be 1,300.degree. C. The upper
limit value of the temperature at the time of cooling the fired
product may be 1,250.degree. C. For example, the range of the
temperature at the time of cooling the fired product may be 800 to
1,300.degree. C. The range of the temperature at the time of
cooling the fired product may be 900 to 1,250.degree. C. When the
temperature at the time of cooling the fired product is equal to or
higher than the above lower limit value (800.degree. C. or more),
the bubbles are easily discharged outside of the upper glaze layer
30. When the temperature at the time of cooling the fired product
is equal to or less than the above upper limit value (1,300.degree.
C. or less), the surface of the upper glaze layer 30 is easily
flattened. A cooling rate at the time of cooling the fired product
may be 30.degree. C./minute or less. The cooling rate at the time
of cooling the fired product may be 10.degree. C./minute or less.
The cooling rate at the time of cooling the fired product may be
0.1.degree. C./minute or less. When the cooling rate at the time of
cooling the fired product is equal to or less than the above upper
limit value (30.degree. C./minute or less), the bubbles are easily
discharged outside of the upper glaze layer 30. In addition, when
the cooling rate at the time of cooling the fired product is equal
to or less than the above upper limit value (30.degree. C./minute
or less), the surface of the upper glaze layer 30 is easily
flattened.
[0091] The sanitary ware 1 may be obtained by applying the
intermediate layer composition to the surface of the ceramic base
material 10 through dipping, pouring, applying, or spraying, and
then firing it to obtain a primary fired body (the first firing
step), and applying the upper glaze layer composition to the
primary fired body and firing it (the second firing step).
[0092] The lower limit value of the firing temperature at the first
firing step may be 800.degree. C. The lower limit value of the
firing temperature at the first firing step may be 850.degree. C.
The upper limit value of the firing temperature at the first firing
step may be 1,000.degree. C. The upper limit value of the firing
temperature at the first firing step may be 950.degree. C. For
example, the range of the firing temperature at the first firing
step may be 800 to 1,000.degree. C. The range of the firing
temperature at the first firing step may be 850 to 950.degree. C.
When the firing temperature at the first firing step is equal to or
higher than the above lower limit value (800.degree. C. or more),
the intermediate layer composition is easily and sufficiently
melted. In addition, when the firing temperature at the first
firing step is equal to or higher than the above lower limit value
(800.degree. C. or more), degassing of the ceramic base material 10
and the intermediate layer 20 is performed so that the mixing of
the pores into the upper glaze layer 30 is easily inhibited. When
the firing temperature at the first firing step is equal to or less
than the above upper limit value (1,000.degree. C. or less), the
surface of the intermediate layer 20 is easily flattened, and the
adhesion to the upper glaze layer composition is easily improved.
The lower limit value of the firing time at the first firing step
may be 1 hour. The lower limit value of the firing time at the
first firing may be 2 hours. The lower limit value of the firing
time at the first firing step may be 3 hours. The upper limit value
of the firing time at the first firing step may be 168 hours. The
upper limit value of the firing time at the first firing step may
be 72 hours. The upper limit value of the firing time at the first
firing step may be 24 hours. For example, the range of the firing
time at the first firing step may be 1 to 168 hours. The range of
the firing time at the first firing step may be 2 to 72 hours. The
range of the firing time at the first firing step may be 3 to 24
hours. When the firing time at the first firing step is equal to or
more than the above lower limit value (one hour or more), the
surface of the intermediate layer 20 is easily flattened. In
addition, when the firing time at the first firing step is equal to
or more than the above lower limit value (one hour or more),
degassing of the ceramic base material 10 and the intermediate
layer 20 is performed so that the mixing of the pores into the
upper glaze layer 30 is easily inhibited. When the firing time at
the first firing step is equal to or less than the above upper
limit value (168 hours or less), productivity of the sanitary ware
1 is easily improved. The primary fired body is obtained by firing
the primary coated body.
[0093] The primary fired body may be cooled before applying the
upper glaze layer composition. The lower limit value of the
temperature at the time of cooling the primary fired body may be
800.degree. C. The lower limit value of the temperature at the time
of cooling the primary fired body may be 850.degree. C. The upper
limit value of the temperature at the time of cooling the primary
fired body may be 1,000.degree. C. The upper limit value of the
temperature at the time of cooling the primary fired body may be
950.degree. C. For example, the range of the temperature at the
time of cooling the primary fired body may be 800 to 1,000.degree.
C. The range of the temperature at the time of cooling the primary
fired body may be 850 to 950.degree. C. When the temperature at the
time of cooling the primary fired body is equal to or higher than
the above lower limit value (800.degree. C. or more), the bubbles
are easily discharged outside of the intermediate layer 20. When
the temperature at the time of cooling the primary fired body is
equal to or less than the above upper limit value (1,000.degree. C.
or less), the surface of the intermediate layer 20 is easily
flattened. A cooling rate at the time of cooling the primary fired
body may be 30.degree. C./minute or less. The cooling rate at the
time of cooling the primary fired body may be 10.degree. C./minute
or less. When the cooling rate at the time of cooling the primary
fired body is equal to or less than the above upper limit value
(30.degree. C./minute or less), the bubbles are easily discharged
outside of the intermediate layer 20. In addition, when the cooling
rate at the time of cooling the primary fired body is equal to or
less than the above upper limit value (30.degree. C./minute or
less), the surface of the intermediate layer 20 is easily
flattened.
[0094] Next, the upper glaze layer composition is applied to the
surface of the primary fired body. From the viewpoint of making it
easy to adjust the thickness of the upper glaze layer 30, the
method of applying the upper glaze layer composition to the surface
of the primary fired body may be spraying (also referred to as
spray coating). The amount of the upper glaze layer composition
applied to the surface of the primary fired body is the same as the
amount of the upper glaze layer composition applied to the surface
of the primary coated body. By applying the upper glaze layer
composition to the surface of the primary fired body, the secondary
coated body is obtained.
[0095] Next, the secondary coated body is fired (the second firing
step). The lower limit value of the firing temperature at the
second firing step may be 1,100.degree. C. The lower limit value of
the firing temperature at the second firing step may be
1,150.degree. C. The upper limit value of the firing temperature at
the second firing step may be 1,300.degree. C. The upper limit
value of the firing temperature at the second firing step may be
1,250.degree. C. For example, the range of the firing temperature
at the second firing step may be 1,100 to 1,300.degree. C. The
range of the firing temperature at the second firing step may be
1,150 to 1,250.degree. C. When the firing temperature at the second
firing step is equal to or higher than the above lower limit value
(1,100.degree. C. or more), the upper glaze layer composition is
easily and sufficiently melted. When the firing temperature of the
second firing step is equal to or less than the above upper limit
value (1,300.degree. C. or less), the surface of the upper glaze
layer 30 is easily flattened. The lower limit value of the firing
time at the second firing step may be 1 hour. The lower limit value
of the firing time at the second firing step may be 2 hours. The
lower limit value of the firing time at the second firing step may
be 3 hours. The upper limit value of the firing time at the second
firing step may be 168 hours. The upper limit value of the firing
time at the second firing step may be 72 hours. The upper limit
value of the firing time at the second firing step may be 24 hours.
For example, the range of the firing time at the second firing step
may be 1 to 168 hours. The range of the firing time at the second
firing step may be 2 to 72 hours. The range of the firing time at
the second firing step may be 3 to 24 hours. When the firing time
at the second firing step is equal to or more than the above lower
limit value (one hour or more), the surface of the upper glaze
layer 30 is easily flattened. When the firing time at the second
firing step is equal to or less than the above upper limit value
(168 hours or less), productivity of the sanitary ware 1 is easily
improved. The fired product is obtained through the second firing
step. The fired product is cooled to be the sanitary ware 1. The
temperature at the time of cooling the fired product is the same as
the temperature at the time of cooling the fired product described
above. The cooling rate at the time of cooling the fired product is
the same as that at the time of cooling the fired product described
above.
[0096] By obtaining the sanitary ware 1 via the primary fired body,
the interface between the intermediate layer 20 and the upper glaze
layer 30 is more easily flattened. By obtaining the sanitary ware 1
via the primary fired body, the number of pores contained in the
intermediate layer 20 and the upper glaze layer 30 is easily
reduced. For this reason, the "depth" of the sanitary ware 1 is
more easily improved. Similarly, by obtaining the sanitary ware 1
via the primary fired body, the interface between the intermediate
layer 20 and the upper glaze layer 30 is more easily flattened. By
obtaining the sanitary ware 1 via the primary fired body, the
number of pores contained in the intermediate layer 20 and the
upper glaze layer 30 is easily reduced. For this reason, the
"beauty" of the sanitary ware 1 is more easily improved. From the
viewpoint of more easily improving at least one of the "depth" and
the "beauty" of the sanitary ware 1, the method of manufacturing
the sanitary ware of the present embodiment preferably obtains the
sanitary ware 1 via the primary fired body.
[0097] As mentioned above, although the present embodiment has been
described in detail with reference to drawings, the present
disclosure is not limited to the above embodiment, and can be
appropriately modified without departing from the scope of the
present disclosure. The components in the above embodiment can
appropriately be replaced with well-known components.
[0098] In the embodiment described above, the sanitary ware 1
includes the ceramic base material 10, the intermediate layer 20,
and the upper glaze layer 30. However, the present disclosure is
not limited to the embodiment described above, and, for example,
the sanitary ware may not have the intermediate layer. The sanitary
ware may have a form in which the upper glaze layer (glaze layer)
is provided on the surface of the ceramic base material. The
sanitary ware may have another glaze layer between the upper glaze
layer 30 and the intermediate layer 20, and the glaze layer may
include a plurality of layers. The sanitary ware may be a form in
which the intermediate layer, a single layer or multiple layers of
the glaze layer, and the upper glaze layer (glaze layer) are
provided on the surface of the ceramic base material. From the
viewpoint of further improving at least one of the "depth" and the
"beauty" of the sanitary ware, the sanitary ware can include the
intermediate layer. In the case where the sanitary ware does not
have an intermediate layer, the thickness of the upper glaze layer
(glaze layer) can be determined, for example, by the following
procedure. The sanitary ware is cut along the thickness direction
of the upper glaze layer using a small sample cutter. The cut
surface after cutting is observed with a microscope (DSX510,
manufactured by Olympus Corporation) at a magnification of 125
times. In the observed image, the distance between a boundary line
between the upper glaze layer and the ceramic base material (an
upper-base material boundary line) and the surface of the upper
glaze layer is measured at any 20 places. An arithmetic average
value of the measured distances is taken as the thickness of the
upper glaze layer.
EXAMPLES
[0099] Next, the present disclosure will be described in more
detail by way of examples, but the present disclosure is not
limited thereto. Raw materials used in these examples are as shown
in the following [Used raw material].
[0100] [Used Raw Material]
[0101] <Ceramic Base Raw Material>
[0102] A-1: 10 parts by mass of china stone, 40 parts by mass of
feldspar, 50 parts by mass of clay (70 mass % of SiO2, 25 mass % of
Al2O3, and 5 mass % in total of Na2O, K2O, CaO, MgO and ZnO).
[0103] A-2: 30 parts by mass of china stone, 70 parts by mass of
clay (65 mass % of SiO2, 30 mass % of Al2O3, and 5 mass % in total
of Na2O, K2O, CaO, MgO and ZnO).
[0104] <Intermediate Layer Raw Material>
[0105] B-1: 65 mass % of SiO2, 20 mass % of Al2O3, 12 mass % in
total of Na2O, K2O, CaO, MgO and ZnO, and 3 mass % of the
others.
[0106] B-2: A mixture of the ceramic base raw material A-2 and the
following glaze raw material C-9 at a mass ratio (ceramic
base/glaze ratio) of 80/20.
[0107] B-3: A mixture of the ceramic base raw material A-2 and the
following glaze raw material C-9 at a mass ratio (ceramic
base/glaze ratio) of 70/30.
[0108] B-4: A mixture of the ceramic base raw material A-2 and the
following glaze raw material C-9 at a mass ratio (ceramic
base/glaze ratio) of 60/40.
[0109] B-5: A mixture of the ceramic base raw material A-2 and the
following glaze raw material C-9 at a mass ratio (ceramic
base/glaze ratio) of 50/50.
[0110] B-6: A mixture of the ceramic base raw material A-2 and the
following glaze raw material C-9 at a mass ratio (ceramic
base/glaze ratio) of 40/60.
[0111] B-7: A mixture of the ceramic base raw material A-2 and the
following glaze raw material C-9 at a mass ratio (ceramic
base/glaze ratio) of 30/70.
[0112] B-8: A mixture of the ceramic base raw material A-2 and the
following glaze raw material C-9 at a mass ratio (ceramic
base/glaze ratio) of 20/80.
[0113] B-9: A mixture of the ceramic base raw material A-2 and the
following glaze raw material C-9 at a mass ratio (ceramic
base/glaze ratio) of 10/90.
[0114] B-10: A mixture of the ceramic base raw material A-2 and the
following glaze raw material C-9 at a mass ratio (ceramic
base/glaze ratio) of 0/100.
[0115] <Glaze Raw Material>
[0116] C-1: 63 mass % of SiO2, 12 mass % of Al2O3, 24 mass % in
total of Na2O, K2O, CaO, MgO, ZnO, SrO, BaO and B2O3, and 1 mass %
of the others.
[0117] C-2: 62 mass % of SiO2, 13 mass % of Al2O3, 24 mass % in
total of Na2O, K2O, CaO, MgO, ZnO, SrO, BaO and B2O3, and 1 mass %
of the others.
[0118] C-3: 62 mass % of SiO2, 13 mass % of Al2O3, 24 mass % in
total of Na2O, K2O, CaO, MgO, ZnO, SrO, BaO and B2O3, and 1 mass %
of the others.
[0119] C-4: 64 mass % of SiO2, 12 mass % of Al2O3, and 24 mass % in
total of Na2O, K2O, CaO, MgO, ZnO, SrO, BaO and B2O3.
[0120] C-5: 57 mass % of SiO2, 10 mass % of Al2O3, 32 mass % in
total of Na2O, K2O, CaO, MgO, ZnO, SrO, BaO and B2O3, and 1 mass %
of the others.
[0121] C-6: 63 mass % of SiO2, 12 mass % of Al2O3, 24 mass % in
total of Na2O, K2O, CaO, MgO, ZnO, SrO, BaO and B2O3, and 1 mass %
of the others.
[0122] C-7: 66 mass % of SiO2, 12 mass % of Al2O3, and 22 mass % in
total of Na2O, K2O, CaO, MgO, ZnO, SrO, BaO and B2O3.
[0123] C-8: 70 mass % of SiO2, 11 mass % of Al2O3, and 19 mass % in
total of Na2O, K2O, CaO, MgO, ZnO, SrO, BaO and B2O3.
[0124] C-9: 63 mass % of SiO2, 10 mass % of Al2O3, 20 mass % in
total of Na2O, K2O, CaO, MgO, ZnO, SrO, BaO and B2O3, and 7 mass %
of the others.
[0125] C-10: 61 mass % of SiO2, 12 mass % of Al2O3, and 27 mass %
in total of Na2O, K2O, CaO, MgO, ZnO, SrO, BaO and B2O3.
[0126] C-11: 57 mass % of SiO2, 11 mass % of Al2O3, 25 mass % in
total of Na2O, K2O, CaO, MgO, ZnO, SrO, BaO and B2O3, and 7 mass %
of the others.
[0127] [Preparation of Ceramic Base Material]
[0128] 1 kg of the ceramic base raw material A-1 and 0.4 kg of
water were mixed to obtain a mixture. The mixture was ground by a
ball mill for 20 hours to obtain a ceramic base material
composition. As a result of measuring the particle size of the
solid content of the ceramic base material composition using a
laser diffraction type particle size distribution-measuring device
("MT3300EX (model number)," manufactured by Nikkiso Co., Ltd.), D50
was 12 .mu.m.
[0129] Next, the ceramic base material composition was poured into
a plaster mold having a length of 100 mm, a width of 100 mm, and a
thickness of 10 mm to obtain a ceramic base material.
[0130] [Preparation of Frit]
[0131] The glaze raw materials C-1 to C-11 were melted at
1,500.degree. C. as frit raw materials to obtain the frits F-1 to
F-11.
[0132] [Preparation of Intermediate Layer Composition]
[0133] 1 kg of the intermediate layer raw material B-1 and 0.4 kg
of water were mixed to obtain a mixture. The mixture was ground by
a ball mill for 20 hours to obtain the intermediate layer
composition M-1. As a result of measuring the particle size of the
solid content of the intermediate layer composition M-1 using the
laser diffraction type particle size distribution-measuring device,
D50 was 8 .mu.m.
[0134] The intermediate layer compositions M-2 to M-10 were
obtained in the same method as the intermediate layer composition
M-1 except that the intermediate layer raw materials B-2 to B-10
were used instead of the intermediate layer raw material B-1. The
intermediate layer composition M-11 was prepared by mixing 1 kg of
the glaze raw material C-11 and 0.6 kg of water as an intermediate
layer raw material to obtain a mixture. In Tables 1 and 2, the
"Type" of the intermediate layer composition represents any of the
intermediate layer compositions M-1 to M-11. The "D50 (.mu.m)" of
the intermediate layer composition represents the 50% average
particle size (D50) of any of the above intermediate layer
compositions M-1 to M-11.
[0135] [Preparation of Upper Glaze Layer Composition]
[0136] 1 kg of the frit F-1 and 0.6 kg of water were mixed to
obtain a mixture. The mixture was ground by a ball mill for 30
hours, and a viscosity modifier such as carboxymethyl cellulose was
added to adjust viscosity, whereby the upper glaze layer
composition G-1 was obtained. As a result of measuring the particle
size of the solid content of the upper glaze layer composition G-1
using the above-mentioned laser diffraction type particle size
distribution-measuring device, D50 was 15 .mu.m.
[0137] The upper glaze layer compositions G-2 to G-10 were obtained
by the same method as the upper glaze layer composition G-1 except
that the frits F-2 to F-10 were used instead of the frit F-1. In
Tables 1 and 2, the "Type" of the upper glaze layer composition
represents any of the above-mentioned upper glaze layer
compositions G-1 to G-10. The "D50 (.mu.m)" of the upper glaze
layer composition represents the 50% average particle size (D50) of
any of the above upper glaze layer compositions G-1 to G-10.
Examples 1 to 18 and Comparative Examples 1 to 2
[0138] [Preparation of Sanitary Ware]
[0139] The intermediate layer compositions described in Tables 1
and 2 were applied to the above-mentioned ceramic base material
using a spray coating method, dried at 60.degree. C. for 1 hour,
and then spray coated with the upper glaze layer compositions
described in Tables 1 and 2, whereby secondary coated bodies were
obtained. The secondary coated bodies were fired at 1,220.degree.
C. for 20 hours to obtain rectangular solid samples of the sanitary
ware.
[0140] <Measurement of Thickness of Upper Glaze Layer>
[0141] A sample of each example was cut using a small sample cutter
along the thickness direction along a plane which passes through a
midpoint of one side of the sample in a longitudinal direction
thereof and is parallel to a width direction of the sample. The cut
surface after cutting was observed with a microscope (DSX510,
manufactured by Olympus Corporation) at a magnification of 125
times. The observed image from one end to the other end in the
width direction was divided into 10 parts in the width direction,
and the distance from the surface of the upper glaze layer to the
upper-intermediate boundary line (L30) was measured at 2 places for
each sample. Distances (L30) in total of 20 places were measured
for one sample, and the maximum value and the minimum value of the
thickness of the upper glaze layer, the difference between the
maximum value and the minimum value, and the average value were
determined. An average value of the distances (L30) was determined
as the thickness of the upper glaze layer. The results are shown in
Tables 1 and 2. In the tables, the term "Difference" represents the
difference between the maximum value and the minimum value of the
thickness of the upper glaze layer.
[0142] <Measurement of Thickness of Intermediate Layer>
[0143] Using the image observed in the thickness of the upper glaze
layer, the observed image from one end to the other end in the
width direction was divided into 10 parts in the width direction,
and the distance between the upper-intermediate boundary line and
the intermediate-base material boundary line (L20) was measured at
2 places for each sample. Distances (L20) in total of 20 places
were measured for one sample, and the average value was determined
as the thickness of the intermediate layer. The results are shown
in Tables 1 and 2.
[0144] <Measurement of First Melting Temperature>
[0145] The intermediate layer composition used in each example was
dried at 80.degree. C. for 2 hours to obtain a sample powder of
each example. A DTA measurement was performed such that, using a
DTA device (TG8121, manufactured by RIGAKU CO., LTD.), 30 mg of
alumina powder (reference substance) and 30 mg of the sample powder
of each example were heated at a heating rate of 3.degree.
C./minute while flowing air at normal temperature (25.degree. C.)
at a flow rate of 200 mL/minute. In the obtained DTA curve, the
first inflection point at which the potential difference .DELTA.V
that appears in the region where the temperature of the reference
substance exceeds 700.degree. C. decreases was obtained, and the
temperature of the reference substance at the first inflection
point was taken as the first melting temperature. The potential
difference .DELTA.V corresponds to a value .DELTA.T obtained by
subtracting the temperature of the reference substance from the
temperature of the sample powder. The measured first melting
temperatures are shown in Table 1.
[0146] <Measurement of Second Melting Temperature>
[0147] In the above DTA curve, the first inflection point (second
inflection point) which appears on a higher temperature side than
the first melting temperature and at which the potential difference
.DELTA.V increases was obtained, and the temperature of the
reference substance at the second inflection point was taken as the
second melting temperature. The potential difference .DELTA.V
corresponds to a value .DELTA.T obtained by subtracting the
temperature of the reference substance from the temperature of the
sample powder. The measured second melting temperatures are shown
in Table 1.
[0148] <Measurement of Average Pore Size, Pore Area Ratio,
Number of Pores>
[0149] Using the image observed with the above microscope, the
image was binarized with device processing software (WinROOF2015,
provided by Mitani Shoji Co., Ltd.). The average pore size, the
pore area ratio, and the number of pores in the cut surface of the
upper glaze layer were determined by performing image analysis of
the binarized image. In addition, the average pore size, the pore
area ratio, and the number of pores in the cut surface of the
intermediate layer were determined. The results are shown in Tables
1 and 2.
[0150] <Measurement of Image Clarity>
[0151] A sample of each example was prepared, and the DOI value was
measured by a Wave-Scan DOI measuring device (Wave-Scan-DUAL,
manufactured by BYK Gardner). The results are shown in Tables 1 and
2.
[0152] <Evaluation of "Depth">
[0153] A sample of each example was prepared, held up to a
fluorescent light in a room, and subjected to appearance
sensitivity evaluation from the viewpoint of feeling the deepness
of light as the "depth" and feeling of the surface cleanness. The
appearance sensitivity evaluation was conducted by 10 subjects, and
the "depth" was evaluated based on the following evaluation
criteria. The results are shown in Tables 1 and 2.
[0154] <<Evaluation Criteria>>
[0155] GOOD: The number of subjects who feel the "depth" is 5 or
more.
[0156] NG: The number of subjects who feel the "depth" is 4 or
less.
[0157] <Evaluation of "Underlayer Blur">
[0158] A sample of each example was prepared, held up to a
fluorescent light in a room, and subjected to appearance
sensitivity evaluation from the viewpoint of feeling an "underlayer
blur" of sanitary ware. Here, the term "underlayer blur" refers to
a blur in a layer (intermediate layer) under the upper glaze layer,
which can be seen through the upper glaze layer on the surface of
the sanitary ware. It is judged by human vision whether the
underlayer is blurred or not. Sanitary ware with little "underlayer
blur" has excellent "beauty." The appearance sensitivity evaluation
was conducted by 10 subjects, and the "underlayer blur" was
evaluated based on the following evaluation criteria. The results
are shown in Tables 1 and 2.
[0159] <<Evaluation Criteria>>
[0160] GOOD: The number of subjects who do not feel "underlayer
blur" is 7 or more.
[0161] OK: The number of subjects who do not feel "underlayer blur"
is 5 or more.
[0162] NG: The number of subjects who do not feel "underlayer blur"
is 4 or less.
TABLE-US-00001 TABLE 1 Example Number E1 E2 E3 E4 E5 E6 Structure
of Upper Glaze Upper Glaze Type G-1 G-2 G-3 G-4 G-5 G-6 Layers
Layer Layer D50 (.mu.m) 15 15 15 15 15 15 Composition Thickness
Maximum 295 275 325 278 360 303 (.mu.m) Value Minimum 265 227 278
240 333 286 Value Difference 30 48 47 38 28 17 Average 282 253 309
269 349 295 Value Average Pore Size (.mu.m) 13 14 14 23 24 17 Pore
Area Ratio (%) 0.43 0.95 1.53 1.32 1.38 1.26 Number of Pores
(/mm.sup.2) 26 41 48 27 16 40 Intermediate Intermediate Type M-1
M-1 M-1 M-1 M-1 M-1 Layer Layer Ceramic -- -- -- -- -- --
Composition base/glaze ratio First Melting -- -- -- -- -- --
Temperature (.degree. C.) Second -- -- -- -- -- -- Melting
Temperature (.degree. C.) D50 (.mu.m) 8 8 8 8 8 8 Thickness Average
512 558 583 508 554 555 (.mu.m) Value Average Pore Size (.mu.m) 14
14 13 13 14 13 Pore Area Ratio (%) 10.65 10.48 8.69 9.10 8.74 9.75
Number of Pores (/mm.sup.2) 440 419 398 443 349 415 Evaluation
Depth GOOD GOOD GOOD GOOD GOOD GOOD Underlayer Blur -- -- -- -- --
-- Image Clarity 92 91 91 94 93 94 Example Number E7 E8 E9 E10 E11
Structure of Upper Glaze Upper Glaze Type G-7 G-8 G-9 G-4 G-4
Layers Layer Layer D50 (.mu.m) 15 15 15 15 15 Composition Thickness
Maximum 328 324 327 225 252 (.mu.m) Value Minimum 299 296 299 170
232 Value Difference 29 28 28 55 19 Average 319 318 311 206 243
Value Average Pore Size (.mu.m) 15 13 12 15 20 Pore Area Ratio (%)
1.31 1.34 1.32 2.30 2.11 Number of Pores (/mm.sup.2) 51 59 69 70 47
Intermediate Intermediate Type M-1 M-1 M-1 M-2 M-3 Layer Layer
Ceramic -- -- -- 80/20 70/30 Composition base/glaze ratio First
Melting -- -- -- 951 925 Temperature (.degree. C.) Second -- -- --
1,235 1,220 Melting Temperature (.degree. C.) D50 (.mu.m) 8 8 8 9 9
Thickness Average 497 511 523 488 504 (.mu.m) Value Average Pore
Size (.mu.m) 14 13 14 8 12 Pore Area Ratio (%) 9.18 9.34 9.74 7.56
9.46 Number of Pores (/mm.sup.2) 417 432 398 613 535 Evaluation
Depth GOOD GOOD GOOD GOOD GOOD Underlayer Blur -- -- -- NG GOOD
Image Clarity 85 85 77 80 85
TABLE-US-00002 TABLE 2 Example Number E12 E13 E14 E15 E16 E17 E18
CE1 CE2 Structure Upper Upper Glaze Type G-4 G-4 G-4 G-4 G-4 G-4
G-4 G-10 G-10 of Layers Glaze Layer D50 (.mu.m) 15 15 15 15 15 15
15 15 15 Layer Composition Thickness Maximum 253 231 199 221 244
265 245 604 1085 (.mu.m) Value Minimum 227 197 159 172 165 187 186
528 0 Value Difference 26 34 40 48 79 77 59 76 1085 Average 242 221
181 214 218 222 225 572 862 Value Average Pore Size (.mu.m) 9 16 19
12 17 14 8 68 60 Pore Area Ratio (%) 0.70 2.82 1.15 2.31 1.41 0.71
0.71 3.29 3.50 Number of Pores (/mm.sup.2) 67 103 30 93 40 35 74 3
10 Inter- Intermediate Type M-4 M-5 M-6 M-7 M-8 M-9 M-10 M-1 M-11
mediate Layer Ceramic 60/40 50/50 40/60 30/70 20/80 -- -- -- --
Layer Composition base/glaze ratio First 938 946 912 864 859 -- --
-- -- Melting Temperature (.degree. C.) Second 1,213 1,214 1,133
1,088 1,027 -- -- -- -- Melting Temperature (.degree. C.) D50
(.mu.m) 8 8 8 7 7 6 6 8 15 Thickness Average 575 596 494 505 566
551 456 576 782 (.mu.m) Value Average Pore Size (.mu.m) 13 16 19 27
20 28 25 14 70 Pore Area Ratio (%) 10.91 11.23 9.76 14.36 12.09
11.36 6.70 7.99 6.00 Number of Pores (/mm.sup.2) 430 269 189 135
149 100 65 298 20 Evaluation Depth GOOD GOOD GOOD GOOD GOOD GOOD
GOOD NG NG Underlayer Blur GOOD GOOD GOOD OK NG -- -- -- -- Image
Clarity 93 89 87 82 80 91 91 70 70
[0163] As shown in Tables 1 and 2, in Examples 1 to 18, the
evaluation of the "depth" was "GOOD," and it was found that the
"depth" had been further improved. In addition, in Examples 11 to
15, in which the difference between the maximum value and the
minimum value of the thickness of the upper glaze layer is equal to
or less than 50 .mu.m, the evaluation of "underlayer blur" is
"GOOD" or "OK", and it was found that the "beauty" had been further
improved. On the other hand, in Comparative Examples 1 (CE1) and 2
(CE2) in which the average pore size in the cut surface of the
upper glaze layer is out of the applicable range of the present
disclosure, the evaluation of the "depth" was "NG".
[0164] According to the sanitary ware of the present disclosure, it
was found that the "depth" of sanitary ware can be further
improved. According to the sanitary ware of the present disclosure,
it was found that the "beauty" of sanitary ware can be further
improved.
* * * * *